I agree with stringent regulations with respect to apps other than interactive entertainment. I disagree about interactive entertainment because I don't think that moral arguments for marketplace regulation extends to video games. Especially when it comes to cross-platform games like Fortnite. Nobody is forced to make games for iOS. Epic Games were certainly not forced to do business with Apple any more than Bungie or Naughty Dog weren't.

Is this distinction you're drawing based on a categorical difference such as entertainment or art? Or is it related to the size of the vendor relative to some metric?

Given that the service operator gates access to the customers and that most customers are unlikely to switch just to do business with a particular vendor, then shouldn't policy be determined solely by the size of the service operator? Why should the type of good or size of the vendor enter into it?

In the west Apple is approximately half of mobile. That's massive. Saying a vendor isn't forced to do business with them is like saying that a vendor isn't forced to sell their products competitively. All things being equal if you publish software for mobile then you will be selling through Apple regardless of the terms they might impose.

Your remark about Bungie and Naughty Dog seems to me like saying that the local city doesn't need to tax a chain restaurant at the same rate as an independent one because it has storefronts in other cities with more favorable terms. The idea being that if they don't like the city's terms they can just close that storefront; it won't kill them due to their size and reach.