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Well, transfers are "reversible". There's nothing technical stopping a bank to wire money back.

But, banks are not allowed to mess with your funds. If it's in you account, then it's yours. It would be illegal for a bank to simply reverse a transfer. Crooks are protected by the laws as well.

Even if some obvious mistake was made at a e.g. payment provider and funds were wired to the wrong bank account, your bank has to send you a letter asking for your permission to reverse the mistake. Reading a batch file twice is a nice example: You get two credit entries, but the bank is not allowed to reverse one.

What happens with smaller scams is that crooks withdraw funds as soon as they've been booked. So most of the time the money already is physically lost before a (legal) claim arrives. So there's that.