I’d note that compounding interest is already a “late fee.” The longer you hold the debt the larger it becomes, exponentially. In a meaningful way late fees are double dipping.

There's a difference between "paying interest because you didn't pay off your entire balance" and "paying a $40 late fee because you forgot the payment was due at 10:59AM Eastern Time and you were an hour late".

I read your comment as trying to troll/lampoon him.

There's times where banks seem to deliberately screw your payments, etc, up. There's no sane legal regime where they should make paying your balance artificially difficult.

Of course they should be able to charge a reasonable amount of interest for the use of credit.