Apple and Google have defended their business practices in letters to the UK Competition & Markets Authority, while rival companies and third-party developers continue to push for mobile market reforms.

The UK CMA, in the midst of its mobile ecosystem market study, on Friday published feedback the agency had solicited about its interim report [PDF], which was posted on December 14, 2021.

The CMA last June set out to determine whether the control Apple and Google exert over mobile operating systems, app stores, and web browsers distorts the mobile market and impairs competition. The agency is also conducting more focused investigations of Apple's App Store and Google's Privacy Sandbox – a set of purportedly privacy-protective technologies to replace invasive third-party cookies.

The competition watchdog's preliminary findings, detailed in its interim report, suggest the CMA believes market interventions are necessary to curtail the power that Apple and Google have over their respective ecosystems.

Remedies being considered include: APIs to facilitate device switching; required support for side-loading, third-party payment systems, and third-party app stores; allowing third-party browser engines on iOS; making certain private APIs public; and app review transparency requirements, to name a few of the possibilities.

Apple and Google would prefer to continue with business as usual, and have said as much in their respective letters to the CMA.

Apple's 47-page letter [PDF] argues the remedies proposed in the interim report (IR) are premature and ill-founded, risk doing more harm than good for competition, and are disproportionate to the actual harm of the company's conduct.

The iBiz, which generated an estimated $85.1 billion in revenue from its App Store in 2021, according to analytics firm Sensor Tower, asks that the CMA give more weight to its positive evidence than the negative gripes of rivals.

"With so much at stake, the final report of the market study must go beyond the acceptance at face value of often self-serving complaints from a limited number of the largest market participants," Apple's law firm Gibson Dunn argued.

"It must hear more from consumers about why they continue to choose Apple devices. The final report cannot rely on hypothetical considerations to the exclusion of positive evidence submitted by Apple, app developers and other interested parties. And it must contain a fuller examination of the implications of the interventions that it is proposing."

Google offers a slightly less spirited defense where its practices – like supporting side-loading and third-party browser engine distribution – already align with contemplated CMA remedies [PDF]. But it too insists there's ample competition and really no reason to meddle with in-app billing.

Rivals like Epic Games, Microsoft, and Mozilla argue more needs to be done to force Apple and Google to release their "vice-like grip," as CMA chief exec Andrea Coscelli put it when the interim report was released.

Epic Games [PDF], currently in the midst of a legal battle with Apple and Google over in-app payment limitations, endorsed the CMA's proposed remedies and argued in favor of alternative in-app payment and app distribution mechanisms. The game maker's letter goes on to assert Apple's security concerns are pretextual and self-serving.

"Apple has consistently represented the Mac as secure and safe from malware, and there are no credible arguments to suggest that alternative app distribution would be less safe on an iPhone than it is on a Mac," Epic said.

Microsoft [PDF] wants Apple and Google to be required to allow developers to use the payment processing service of their own choice; to allow third-party app stores; to permit side-loading; to improve support for web apps; and to allow native cloud gaming apps. It too argues that the security issues raised by Apple are "overstated."

Mozilla [PDF] makes a pitch for CMA intervention in the mobile browser market, which is to be expected given how Apple's iOS browser engine restrictions have limited Firefox on Apple's mobile devices. It also defends the deprecation of third-party cookies that Google's Privacy Sandbox intends to replace.

The recently formed Open Web Advocacy group argues that gatekeepers should be required to provide browser vendors with all functionalities available to any app or service provided by the gatekeeper or their business partners; to support third-party browsers engines on iOS; and to provide web app support in mobile operating systems.

The group points to Apple's "utter contempt" of Dutch regulators – which have required Apple to support third-party payment systems and repeatedly fined Apple for failing to do so – as evidence that regulatory remedies need to anticipate bad faith behavior.

Quite a few other organizations have weighed in, as have individual web developers.

For example, Alistair Shepherd, a UK-based front-end developer at London-based web agency Series Eight, said he agrees with the CMA's interim report about the impact of Apple's iOS browser limitations.

"Although we build for all modern browsers, a significant amount of time in site development is spent catering for and fixing bugs specifically caused by Safari on iOS," claimed Shepherd [PDF]. "Every client we build a site for will pay for roughly one week of full-time work in testing and bug fixing, and generally about 75–80 per cent of this is spent on iOS web bugs. The current state of Safari directly costs Series Eight time and money for every project, exacerbated by the poor documentation, update logs and private bugfix boards for Safari."

Kimberly Blessing, head of technology for Glasgow-based Dog Digital Ltd, offers a similar assessment of Apple's browser rules. "From a business perspective, developing Web products is more costly because of Apple’s practices," she wrote [PDF]. "Their Safari browser lags behind other software products, both in terms of unresolved bugs and support for common features available on other platforms."

But not everyone believes Apple's browser rules should be challenged. Chris Jones, who works for Red Hat in the UK and contributes to open source projects, insists that Apple's WebKit requirement is actually the only thing keeping Google's Chromium (based on a WebKit fork called Blink) from taking over the entire browser market.

"As much as my FOSS instincts tell me that iOS should allow competing browser engines, I think the larger picture here is that if [Apple is] compelled to do so, Google will quickly capitalize on the opportunity to drive [its] browser market share closer to 100 per cent," Jones wrote [PDF].

The CMA's final report is due to be published on June 14. The conclusions of the report will not necessarily change anything, but will provide the UK's recently formed Digital Markets Unit and other interested lawmakers with regulatory guidance. Maybe something will come of it. ®