iOS most certainly does not have real sideloading. You can if you recompile the app with your own key every 7 days. Or you can use testflight with some very serious restrictions like not being able to monetize at all.
It’s completely reasonable that side loaded applications should not be entitled to use regulated payment services.
Edit: Even Android will not entitle side loaded apps for Google payment processing. Android and iOS are literally identical in this regard.