From what I gather in the US issues are e.g. weird shit banks do when processing checks and other payments, e.g. reordering transactions to generate unneccessary overdraft fees.
In Germany we for example long had the problem that ATMs of banks not in your network (e.g. when using a Deutsche Bank ATM with a Sparkasse card) were not required to show the fees associated with withdrawing cash. IIRC it needed EU regulation to finally fix this.