Paycheck to paycheck customers have low bank balances, so the interest rate doesn't matter because there's no principal. The banks could have them as customers

Paycheck to paycheck customers have low bank balances, so the interest rate doesn't matter because there's no principal. The banks could have them as customers because of debit card fees paying the costs. But they became unprofitable overnight when the Durbin amendment went into effect, which is why banks started to implement monthly fees (in addition to overdraft fees etc). Yes, credit unions and neobanks can charge higher swipe fees so they can bank them. But under this new proposal, maybe not anymore.