I do online banking on my phone. There's two reasons for it:

1) Because of regulations, I need to use my phone to log in into internet banking and to confirm every transaction (including online card payments) anyway. If I already have to find a phone, I might just use it all the way.

2) Invoices have QR codes on them nowadays, that you can scan with your phone and it will prefill all the account numbers, amounts, etc. That's easier than copy-pasting or rewriting it.

Now this is all actually terrible, because to live in a society, you need a bank account, and to have a bank account, you need Google or Apple-controlled smartphone. (there are some legacy banks that allow you to use SMS for second factor, but it's less and less common)