I’ve used it. It’s not the end of the world. You do have to configure Android to allow installation from “unknown sources” in order to use it, but you can also revert the setting (to block unknown sources) when you’re not actually installing an app, if you are worried about malware auto-installing something.
Personally, I think there’s a happy medium here. Apple (or Google, for that matter) doesn’t need to remove all access controls in order to permit third-party app stores. You can instead make “install software” another permission that an app needs if it is going to be allowed to install additional apps. With such a feature, legitimate app stores (like Amazon or Samsung or your wireless carrier) can install your purchases without permitting everything in the world access.
Yes, a user might be tricked into installing a malicious app store, but there’s no way to avoid that. It didn’t destroy the Windows platform (where malware is a far bigger problem), it didn’t destroy the Mac platform and it won’t destroy iOS. And those that don’t want to trust third-party app stores can use the existing permission mechanism to block apps from installing additional apps.
And, of course, there is no reason why iOS can’t still require apps to be signed and notarized even if they are distributed by a third-party store. Gatekeeper on macOS does this and it seems to work just fine.
It’s been a while, but I don’t think so. But they don’t cost the same. Amazon offers discounts and promotional pricing that isn’t always mirrored on the Google store. Back when my personal phone was Android (admittedly, several years ago), I used both Google and Amazon for my app purchases.
No different from any other computer platform. Macs aren’t the wild west despite the fact that anyone can install apps from any source. Gatekeeper is sufficient to make sure you really really mean it when you try to run an app that isn’t suitably signed, but it lets you make the final decision.
I see no reason why a similar mechanism couldn’t be done for iOS. Yes, some people will be fooled into installing the mega-virus-spam-adware app, but the only way to protect those people is to block all third party apps completely. Ultimately, you have to treat your customers as adults and your customers need to deal with the consequences of making bad choices.
I think it would be perfectly fine to treat iOS like macOS - allow installation of signed and notarized apps from any source, but require users to jump through a few hoops before they’re allowed to install apps that are unsigned or have self-signed certificates.
But I’m 99% certain that Apple has motivations that go beyond system security. And I’m even OK with that, but I wish they would admit it and stop pretending that their motives are purely altruistic.