An alt-store stands to capture more value on iOS than Android, and spying on iOS users is probably a whole lot more lucrative than spying on Android users.
That, combined with the App Store restricting spying more than the Play Store does, is why we can't necessarily expect the iOS ecosystem to behave the same way as Android's, were iOS to get similar side-loading capabilities. A common argument goes that nothing will change on iOS, because it hasn't on Android, but the two markets are different enough that I don't find that a strong argument. Maybe it'll turn out to be right, but I don't think it's as much a slam-dunk argument as those advancing it seem to think it is.
That, combined with the App Store restricting spying more than the Play Store does, is why we can't necessarily expect the iOS ecosystem to behave the same way as Android's, were iOS to get similar side-loading capabilities. A common argument goes that nothing will change on iOS, because it hasn't on Android, but the two markets are different enough that I don't find that a strong argument. Maybe it'll turn out to be right, but I don't think it's as much a slam-dunk argument as those advancing it seem to think it is.