You don’t understand, because side loading in iOS doesn’t not work like it does in Android - not even close. Side loading in iOS is full of restrictions, apps that only work for 3 days and require reinstall etc. And it all still requires binaries to be signed with a valid certificate approved by Apple.
Apple carefully made it in a way that complies with the law but doesn’t really change anything. And imposed small charges and requirements here and there com make it totally impractical.