That it works for you is fine. You obviously have no incentive to look further than what works for you and you are fine with paying 30% for a service that is not competitive but that is convenient.
If you were a bit larger that equation would change. Your first step would then be to use a commercial payment services provider such as Stripe, Adyen or any of the others to process the transactions for you (rates: 1 to 5%), possibly falling back to Apple in case their coverage doesn't perfectly overlap. Then at an even higher level of transactions you could choose to do the payment processing yourself.
It's pretty simple, really. And as for taxes: that too is something that you can arrange in different ways, depending on where your main place of business is registered.
My dismissive tone is because it appears that you want me to do a bunch of homework for you while at the same time arguing that there is nothing to be concerned about in 10's of comments in this thread. You have already made up your mind and seem to use questions as a way to argue rather than that you are really interested in the answers. I predict that as a result of this response you are going to come up with another set of questions for me to answer or a new set of arguments that move the goalposts away from your previous claims.
But the essence of my response is: anti-competitive behavior can not be argued for by utility to some subset of the customers. The phone company provides a lot of value. But if they behave in an anti-competive way, for instance by price gouging customers on something that costs them peanuts such as roaming then they deserve to be smacked down, even if some people will argue that you could of course buy a different phone for every country as an alternative, and so those roaming charges are acceptable because they are cheaper. That misses the point entirely.