I don't know why we can't just have the fees come on a deferred basis

The other guy already said it but I'm going to reiterate for emphasis:

Banks are not your friends. Banks (in the US) exist as for-profit businesses to make money off of you

Edit for clarity: The main way banks make money off of you is by investing the actual cash you give them and agreeing to cover your day to day costs of living. Since the vast majority of people prefer to have a positive bank balance and possibly a savings, it works out that the banks always have money to invest.

It stands to reason that anyone with a negative balance is actively infringing their strategy to invest excess money, so why wouldn't they charge them? It's all business.