Earlier quoted context omitted.
Sandboxing had nothing to with any app store, and Android security empathetically doesn't suck.
I just had a coworker say that he surreptitiously installed an app on his son’s phone that allowed him to see everything his son was doing remotely and listen in to his son’s conversations. He showed it to us in action.
Sure, Apple might prevent you from installing such applications on devices (though they offer monitoring app usage and websites for parental controls), but that's just because they have a walled garden that could disallow such apps and it's less clear how to weigh app freedom against user safety.
If you're worried about zero days, Android exploits are priced around the same as iOS exploits apparently so take that how you will.