App stores need heavy regulations. It's not only Apple but Google and even steam to a small extent. Apple is of course the biggest offender as they heavily guard their monopoly with code signing enforcement. This shouldn't have been legal. They are the very definitions of predatory competition squashing monopolies.
Traditionally the company that develops a product gets to decide what features that product has. There are various laws that require a product be safe to use, is not misrepresented and does what it is advertised to do, but beyond that there are very few actual features of products that they are required by law to have. Maybe some standards they need to meet.
Sometimes companies will invite other companies to join them in adding features to a product. A TV company might add licensed audio technology from Dolby, a car company might add licensed software for infotainment or navigation software, and they may charge their customers for the added software features.
This is how games consoles work, you buy the console from the manufacturer, who licenses other companies to write games for their product as add-on modules. In the past CDs and cartridges were used, but now this often happen via downloads. These games are developed using the console manufacturers tools, run against their code libraries on the device and are clearly an extension of their product. This has been an established approach for many decades. When my kids were toddlers I bought an educational toy where you could buy little cartridges for it that added educational features.
That's all the App Store is. It's a feature added by Apple to their product for adding optional features to the device. As in many cases in the past, across many types of device, this is a feature added by the manufacturer and your relationship as a customer remains with them.
There is no law requiring that a device containing a computer, be it a car, TV, games console, phone or whatever have any specific features to enable loading additional software. That's just not a requirement that exists, and if a device does have a mechanism to add or update its software, there are no laws about how that must or must not be implemented, that I'm aware of anyway.
If you disagree that this is the way it should be that's fine, that's absolutely your right, but can you explain how such laws should be drafted. What kinds of requirements should be put on manufacturers? Under what criteria should they apply and to what devices?
If you think Apple has failed to comply with some law in the way they implemented their products, I'd appreciate some clarity about exactly what you think Apple has done wrong, and how that should be redressed.