Exactly. It's my own device, I can do whatever I please with it. There shouldn't be an automated way for apps to check if my device has been blessed by the US tech giants or not.
I don’t want _all_ my devices to behave like that but I definitely want my phone to be more trustworthy for banking and government service purposes.
You can still do this by simply not rooting your phone, or replacing the manufacturer's cryptographic key with your own, or altering whatever other 'security' measures are in place. What you're asking for is to have no other choice but to give the manufacturer control over your devices.
The problem is that manufacturers are forcing everyone into this scheme for the express purpose of mass surveillance and control.
It has nothing to do with making your device "secure"