Many banks charge a daily overdraft fee on days they are open for business. There is CFPB touted guidance from the FDIC's Kansas City office that explains the pitfalls.
Here. In each and every context, an overdraft is a loan and should be evaluated as such.
Personal opinion strongly held: A daily fee is about the time value of money, not a service, and should be subject to TILA and state usury laws. The agencies have not chosen to take that approach, but they are getting smarter all the time.