You are paying extra when purchasing via any retailer online or not, not just Apple. Only thing that really changes is how much you pay. It really doesn't matter if it is Amazon, Walmart, Kaufland, Google, Microsoft, Steam, Epic store...etc. you always pay extra for privilege of using their store. If you pay by credit card for anything, you pay extra. Some retailers are not accepting credit cards because of that. Same goes for Apple Pay. You pay extra. Prices are already higher for you as a customer, so you may not realise that the price you pay is not going fully to the seller who made the goods.
When Apple store in 2008 was created it was god send for mobile developers. 70/30 split was very good deal. Not many people realize that situation was much worse for developers before appstore. As developer you were lucky if you got 30%. For example: Nokia OVI store, payment made with premium SMS, for 1$, developer could get 30 cents, Nokia took 30%, network operator took 30+% depending on country, for example in Turkey it was 50% and you still have to pay taxes. Fun, right?
There is still option for "dating apps" to go Netflix route, where you have to pay on their web site, and app is just for using it, but you are not doing any transactions there. But they want a cake and eat it too. Not going to fly. Especially in Europe where Apple is in many countries under 20% of market share.