The fundamental difference between us, then, is that for me a banking app being up there with the rest would be other apps being more like Monzo and removing some of the unnecessary barriers to access 
- When N26 were still operating in the UK I got locked out of their app because I used it infrequently enough that the lock pattern reset and I forgot my PIN.
- When my old phone broke, getting the First Direct app working on my new phone was a MASSIVE pain in the bottom that required resetting the tens of different passwords they use in order to be able to have them deactivate the app over the phone so I could reactivate it on my new phone
- Updates have logged me out of my Halifax and MBNA apps. I need to use my password AND memorable information to log back in, so I haven’t bothered (these cards get paid off by DD anyway)
None of these barriers make the apps any more secure for me, and in the majority of cases they actively put me off using them. Monzo, on the other hand? Easy as, and still secure.
I’m not worried about the lack of a PIN on the app as my phone has a PIN, it locks at the drop of a hat (low inacitivity timeout, locks instantly when turned ‘off’, and I turn it off every time before I put it down).
In a nutshell, I don’t think either of us a ‘wrong’, necessarily. Rather, we’re two different customer profiles. I’m a customer who is a good match for Monzo; you’re a customer who, if the issue is that important to you and you’re not willing to use phone locking or security features to manage the app instead, maybe you’re a better match for another bank. As I’m fairly certain that Monzo is betting there are lot more customers like me out there.