I was trying to explain this to a colleague who trades currency in a small way ($10,000 is small?)

It is not a zero sum equation. They (banks or whatever) take a cut to pay for the processing. The problem is that banks have learned from the crooks. Crooks (the crooks) eat into the margins. The crooks (the banks) claw it back, from you.

If there is no complaint, there is no misdemeanor. You want to argue? - find someone who is bigger than them.