Not OP, but sharing the sentiment (never had banking or similar software on a phone, yet using ATMs, banks' web interfaces, offices). Avoiding interaction with a bank completely is rarely viable these days, and they will run their software on their hardware to operate either way (whether it is an ATM, a bank office, or a website). I do not see it as relinquishing control of the hardware, since you are not expected to control a bank's hardware in the first place. While setting it on your phone comes with the usual risks of running proprietary software on your machines, such as sneaky data collection. If banks/governments will give mobile devices to people for that, those may act even a little more like electronic ankle bracelets, but they would also be isolated from your other data and software; in places with near-mandatory government software, some choose to create such an isolation by having multiple devices for different purposes.