The DMA Did Not Ask Big Tech to Comply. It Made Them Rebuild.

Based on the research ofStiehle, Funke, Lago, and Weber, "Designing Value-Based Platforms: Architectural Strategies Derived from the Digital Markets Act," arXiv preprint, 2026

On 6 September 2023 the European Commission designated six companies, Alphabet, Amazon, Apple, ByteDance, Meta, and Microsoft, as "gatekeepers" under the Digital Markets Act, and it did not name the companies in the abstract. It named twenty-two specific components: Google Search, Google Play, Google Maps, Google Shopping, YouTube, Android, Chrome, and Alphabet's ad network; Amazon Marketplace and Amazon Advertising; Apple's App Store, iOS, and Safari; TikTok; Facebook, Instagram, WhatsApp, Messenger, and Meta's ad service; LinkedIn and Windows PC OS. Apple's iPadOS was added as a twenty-third core platform service on 29 April 2024, and Booking.com joined as a seventh gatekeeper on 13 May 2024. A new paper by Fabian Stiehle, Markus Funke, Patricia Lago, and Ingo Weber argues that this granularity is not incidental. Because the DMA is written at the level of platform components, a search engine, an app store, an operating system, a browser, its abstract legal values (fair practice, contestability, user choice) can be, and in practice were, translated directly into architectural strategies rather than into a policy memo. The authors derive eight such strategies from the statute's text and fifteen concrete tactics from how gatekeepers actually built compliance. The past two years of DMA enforcement supply an unusually clean, verifiable record of what happens when that translation goes well and when it does not.

Two Companies, One Legal Duty, Two Different Blueprints

Apple and Google faced the same obligation, let developers reach users and process payments outside the platform's own channel, and answered it with opposite architectures. On 25 January 2024, Apple announced its DMA compliance package for iOS 17.4: more than 600 new APIs, a framework for building alternative app marketplaces, support for browser engines other than WebKit, and a new fee structure. Developers who adopt the new EU business terms pay a reduced App Store commission of 10 or 17 percent, plus an optional 3 percent payment-processing fee, plus a Core Technology Fee of €0.50 for every first annual install once an app passes one million installs in the EU in a year. That last number is the load-bearing detail: the fee attaches to installs, not to revenue. A free, ad-supported app distributed through an alternative marketplace, precisely the kind of complementor the DMA's alternative-distribution rule is meant to enable, can owe Apple money before it earns a cent.

Google's architecture for the same underlying duty ties the toll to the transaction instead of the install. Since March 2024, developers in the European Economic Area can route in-app purchases through their own billing system rather than Google Play's, and Google's service fee on those transactions is cut by three percentage points versus the standard rate; a companion "external offers" program lets developers point EEA users to cheaper deals on other storefronts or their own website. There is no per-install fee sitting between a new entrant and its first paying customer. Same statute, same category of obligation, and two structurally different cost curves facing anyone trying to build a business on top of the platform. The paper's claim that architecture, not policy language, is where DMA obligations get operationalized shows up here as a simple, checkable fact: read the fee schedule, and you already know which platform is trying to grow a complementor ecosystem and which is trying to preserve one.

The €500 Million Fine Was for a Fee Structure and a Screen

The European Commission's April 2025 enforcement actions make the same point even more directly, because in Apple's case the Commission fined the architecture, not the statute. Apple was fined €500 million for breaching the DMA's anti-steering rule, which requires letting developers tell users about cheaper offers outside the app. Apple's technical answer to that rule, rolled out through 2024, was not a refusal, it was a specific design: an in-app "disclosure sheet" that interrupts the user before they follow a link out of the app, plus a 5 percent fee on digital-goods sales completed within twelve months of the linked-out acquisition, plus an additional 10 percent "store services" fee on purchases made through that link-out. The Commission's finding was not that Apple broke the law by writing bad legal language; it was that the fee structure and the screen's design and timing amounted to a restriction the law prohibits, and it ordered Apple to remove those specific "technical and commercial restrictions" within sixty days. Meta was fined €200 million the same week for a parallel architectural choice: its November 2023 "pay or consent" model on Facebook and Instagram, which gave EU users a binary interface, accept personalized-ad data use or pay roughly €10 a month, rather than a genuinely equivalent, lower-data option the Commission said Article 5(2) requires.

The €500 million fine did not target Apple's compliance policy. It targeted the fee percentages and the screen a user sees before leaving the app.

The Same Day, the Same Company, Two Opposite Verdicts

The clearest evidence that architecture is where DMA compliance gets adjudicated is that Apple received two opposite rulings from the same regulator in the same week. Alongside the €500 million steering fine, the Commission closed its separate non-compliance procedure against Apple over Article 6(3), the provision governing default-setting and browser choice screens. That case had opened in March 2024 after regulators found Apple's original iOS 17.4 choice screen, shown once, the first time a user opened Safari, made it too hard to actually switch. Apple's answer was three further rounds of architectural revision: in August 2024 it announced a redesigned screen for iOS and iPadOS 18 that let users select a browser directly from a left-hand toolbar, pinned that selection to the top of a scrollable list of the twelve most-downloaded browsers in each country, pulled in richer per-browser descriptions, auto-downloaded and auto-defaulted the chosen browser on confirmation, and, crucially, began showing the screen again on every device where Safari remained the default, not just once per user ever. A further round followed in October 2024. By April 2025 the Commission judged the redesigned architecture sufficient and closed the case. Apple did not win by lobbying the definition of "user choice." It won by rebuilding the screen three times until the mechanics of the screen itself satisfied the regulator watching how users actually moved through it.

What This Means for Anyone Building Inside a Regulated Platform

The operating lesson generalizes past app stores. When a legal value like "fairness" or "contestability" gets imposed on a platform, the platform's engineering and product teams, not its legal or policy team, end up deciding, tactic by tactic, whether that value becomes a market outside developers can build in or a fee schedule they pay to enter it. Google's alternative-billing cut and Apple's per-install Core Technology Fee both satisfy the letter of "allow alternative payment and distribution channels," yet one is measurably cheaper for a small complementor to test and the other is measurably more expensive, and no amount of policy language distinguishes them, only the architecture does. Any team asked to comply with a DMA-style obligation should treat the compliance mechanism itself as the product decision it actually is: a fee tied to revenue instead of installs, a default screen redesigned until independent measurement shows it works rather than merely exists, and a steering path that a regulator, a developer, and a user would each recognize as genuinely equivalent rather than technically permitted. The DMA gave six companies the same abstract instructions. Their architectures, not their lawyers, are what answered.