And more importantly I didn't ask what the user is picking or not picking, I'm asking: why is there an app store out there that's better than the main one? Is a 3rd party app store going to spin up a CDN, a transactions system, handle the customer service involved there, etc. and then just... not do all the evil shit Google and Apple are doing now, which is why their app stores make so much money? You're asking businesses to enter a market with established competitors with solid and wildly profitable business models, and to just have them make less money for the principle of it. Which like, I agree with, but you're gonna have a SHORT list of investors if that's your pitch.
But Google has agreed to distribute app stores (in America anyway) for a modest $5000 fee + $5000/year fee + transaction fees.
Competition is what stops the exploitation.
Epic Games has always offered lower fees and their CEO has been advocating for small developers for years.
There is no reason why Google and Apple get to bundle their stores, and these other big names have to collect the scraps from users who care to look up alternative stores and go through scare screens.
And they created the hardware and software to make all this possible.