> I do not get what's special about banking apps as opposed to online banking.

I use both. In the beginning I used to prefer the web version. I can use my large monitor to see more data and use a full keyboard and mouse. But I have started to use the mobile version more. For Wells Fargo at least, the mobile version is faster to log into because of face ID support. The website requires a lot more clicks and keystrokes. Also, the mobile app makes it easy and possible to deposit checks if and when I get them.