Google is not to blame for the fact that your bank won't trust you to verify an apk signature. There's no fundamental need for the OS vendor to oversee app distribution.
Definitely. Blackhats are much better at overseeing application distribution than the OS vendor. :P
In all seriousness, you already have to trust the OS vendor not to be trying to do bad things. Having them oversee software distribution at least does not increase the number of organizations you need to trust. If you have someone else do it, you will be opening the door to black hats that will be clamoring to take that role. Not relying on the OS vendor to do that is how we have scams where the victims installed the malware that harmed them. :/
