> On that topic, an honest question: what is the killer feature of banking apps that everyone is so hot on? Are we talking like retail banking or money transmitters? I am not using any bespoke banking apps, and I don't feel like I'm missing out, but maybe I just don't know what I'm missing.

For me, the killer "feature" is that I need to generate an auth code on my bank's app to be able to log in to my account and make transfers via my browser (or I can use the app directly). In other words, it's considerably more difficult to actually do (retail) banking without my bank's app.