As far as I remember, last time I needed to use Google play on a shared phone I could just create a random Google address (I mean, completely invented name, etc.) and it allowed me to do anything, just as my normal Android.

I am too lazy to test, but did this change? Can't you just make a "fake" account and continue with your life? The phone company knows where you are, the bank knows what you purchase. Compared to that Google will know far less (ofc, if you don't activate everything)

I find it much more insane that it was possible for so long to do banking WITHOUT strong authentication (however implemented) by just providing those 3 numbers on the back of the card (strong security!)

No, they will either immediately or shortly thereafter require you to link a phone number, etc