The reason is incentives and lack of protections. If banks don't eat the cost of fraud they don't properly protect people from being preyed upon.
Some much for freedom of choice. We the state, decided that you can't be trusted with making decisions about who to transact with, so we mandate that you use a transfer service with arbitration/escrow so you won't be financially harmed. It doesn't matter if you're sending money to a landlord that you lived at for a few years, or splitting a restaurant bill with friends. You must use a transfer service with this service provided, and pay the 1% fee used to fund such a scheme (note this is actually less than credit card interchange, which is around 2-3%).
You say this like these regulations magically just appeared fully formed from the head of Zeus ...
These regulations exists precisely because the fraud was rampant enough that it became a sufficient threat that people would quit using the financial system altogether.
What do you think that means?