The mechanics of how the fee is charged don't determine what it is for. This is like saying Amazon charges you a $49 fee to use their checkout page when ordering a book.
> Your example VS Code is not related to that at all, because Microsoft doesn't prevent installing applications built with other tools. Same with the Epic game engine. Windows/Android/etc don't force you to use the Epic game engine for all games built on their platform. You can use any other technology of your choice.
Nobody is forcing you to use Apple's SDK, either: You are free to use open-source software or to write your own... Of course those tools do not exist today, and your PM probably wants to ship the app sometime this decade. Nothing stops you from doing it yourself, but you would save a lot of work if you use Apple's. This is like complaining that your neighbor built a nice house and now he won't let you live it in for free when you are not willing to do the work to build your own house.
> Even if I build an application completely without the Apple SDK, just with open source software, I can't sell it to people without paying the "Apple tax".
Irrelevant. As of today there is no distinction between "an iOS app" and "an iOS app made using Apple's tools which attracts a fee from Apple".
Anyway, you are trying to diverge from the point: As I stated before, if the EC declares Apple's fee illegal (when there is no alternative tool), that sets a precedent that you cannot charge reasonable fees to license intellectual property. That is contrary to the aim of the DMA to encourage the European tech industry. Thus, predict they will make no attempt to close this supposed loophole.
Additionally, the actual DMA, as far as I can tell from English Wikipedia says nothing about gatekeepers charging fees generally, nor allowing free side-loading specifically.
> In the EU for example all car manufacturers need to provide documentation and spare parts to third party shops.
And those parts are free (as in beer)? No, you pay a reasonable price for them. Here is just the same. Third party software shops pay a reasonable fee, and then do whatever they want with the parts Apple provides. In this case the documentation fee is $99, plus $0.50 per part. If you are a registered non-commercial entity, Apple will even give you the parts for free.
> I know that this kind of "market freedom" is something that doesn't feel right for US citizens.
You mean the kind of market freedom where Spotify (with a 70% market share) is not a monopoly (sorry, "gatekeeper") and Apple (with a 30% market share) somehow is a gatekeeper? Spotify had over $13B in revenue, but paid just $9B to record companies last year. Won't anyone think of those poor record companies that have to pay *35%* "Spotify tax"? Doesn't anyone care that Spotify prevents record companies from having a human relationship with their listeners (and offering Exceptional Customer Service)? Oh, wait, I forgot: they're Americans and the gatekeeper is based in Sweden, and maybe someone is a friend of a friend, so we don't care right?
Yea, I guess I don't mind when the government doesn't have the "freedom" to arbitrarily decide who its friends and enemies are. Rule by law, not by man. Due process and all that. Y'all should try it over there sometime.