But you know who customer X is and if he obtained the money fraudulently then the bank (or police, courts, etc) can go after him to recover it. It might not happen but it's possible.

Same statement could be said about you no?

You're the one that was defrauded. The bank processed the transfer exactly as you told them to. So therefore, if person X isn't providing the service you expected then you should have to go to the courts to get it back?

The general problem is that it takes a lot of leg work. Often Customer X was being defrauded through some payroll scam (they take out ~500 and forward the remaining 1500). So now you have to recover $500 from them and then trace the 1500 again. Possibly through multiple countries and their courts (who may see this as beneficial for their country; jury nullification goes both ways).

Correct, but there are possibilities and established processes (however unlikely or inconvenient) to get the money back.