0. don't tell the customers that we can do anything we can't do
1. cap profits at a low percentage of the capital base to discourage being irresponsible with customer money; enforce corporate austerity to keep costs very low
2. any profits over the cap are returned to customers
that's it, i think. the idea is to have a bank that is rock solid (even when compared to other banks) and profitable for customers. maybe only offer one type of account, and have no minimum deposit. no fees, and offer ATM cost refunds. no personal loans. no credit cards. maybe offer a mortgage package, but probably not. no branches, obviously. customer service would be top priority.
the corporate side of the bank would ride on austerity. no advertising beyond what is necessary to start the bank in motion. no luxuries for the c-suite. maybe enforce a max disparity in pay between the lowest rung and highest rung of employees to something outrageously constrained like 10 or 20k. maybe only have five or six job titles in total, if possible. fill those jobs on a first (somewhat qualified) come first serve basis and a 20 minute interview. advertise the jobs only as necessary.
is this idea crazy? maybe in the banking sector it might be, but you can't trust them. they're drunk on chasing money, and they're reliably unreliable in the long term-- the article even mentions how many banks have gone under.
but there are a lot of great examples of other kinds of companies (i am specifically thinking of the food wholesaler called aldi) which make their money by offering what the customer needs and nothing more. you don't need to go crazy profiteering to make robust profits...