There's nothing complex and impossible about removing some "if" statements responsible for code signature enforcement.
https://developer.apple.com/documentation/browserenginekit
They needed to engineer, maintain, document and support a whole class of APIs so that third parties can create their own competitive browser engines (that offer JIT, etc) while still maintaining iOS sandbox security. There are going to be hundreds of frameworks, thousands of APIs, that will need to come to ensure compliance with the DMA
We believe in the same thing, our devices should be free like speech. But the whole thing turned into a show because some rich software companies don’t want to pay Apple 30% while they have no problem with other platforms like gaming consoles.
Apple initially did that to protect the ecosystem from malware and make sure all apps meet their quality standards. Also to make distribution easy for indie developers. All commendable goals. But as the iOS market share grew, this turned into a very convenient revenue source that they can't let go now.
The digital market should be regulated for sure but what’s happening is a bunch of companies who are in the digital market (and not regulated themselves) exploiting the public sentiment and the regulatory processes.
Spotify and others fail to mention that they were able to access billions of Apple customers without paying a single dime to Apple initially which is unheard of in business relationships.
The whole "user agreement" thing is one of the biggest problems, because it means Apple thinks you buying an iPhone doesn't inherently entitle you to the advertised functionality of it.
Which is, to out it mildly, highly misleading and potentially illegal. The "small print" shouldn't contradict the big picture. You can't pretend you're selling a device and then turn around and declare that those sales were only about raw hardware and not actual functionality. That's not how products work, and most importantly, not how consumer protection laws see it.
The reason why Apple is so adamant in this line of reasoning is clear once you factor in the App Store rationale. From that perspective, any time a third-party app runs on a user's device and calls iOS APIs in order to actually function, it's not part of what the user actually paid money for. Any execution of any software that uses those APIs is an additional transaction altogether, dealt with separately through the iOS EULA. In short, Apple's position is that any time iOS does anything, either by default or powering a third-party app, it's not actually part of the functionality that was paid for in full by the iPhone's owner, because the owner never paid for ANY functionality at all, only the hardware.
According to the App Store policies, if I remember correctly, technically all the customers belong to Apple. Although, the developers are also correct to see it the other way around as well.
The ecosystem was built on the assumption that hardware would be sold with its own profit margin and software would have its own separate profit margin to sustain its own operations, tools, and libraries.
The DMA made the entire software branch unsustainable and everybody thinks that Apple earned enough and they should give the software for free. Well, it's their platform and they're entitled to profit from it as they're pleased. Even the European Commission admitted that as well, because saying otherwise is akin to confiscating their intellectual property. I wouldn't bet the house on it but I think Apple would give up the European market before the core technology fee.