I really have no idea why big banks have any small customers.
If you're just a person, or maybe even a small business, the big commercial banks offer you no value.
I joined a local credit union when I saved up some lawn-mowing money about age 11. It's the only financial institution I've ever needed.
Savings, checking, CDs, car loans, mortgage. ATMs, credit card, debit card when that became a thing, online banking when that became a thing.
I even used Zelle on the credit union website to send a coworker money a few years ago.
It requires a special kind of ignorance to keep paying the fees and living with the restrictions of those big banks.