[bityard]

They certainly try. But it's not like there are no protections in place.

The US banking system can be summarized as "withdraw first, ask questions later." The whole system is based around auditing after the fact. If at the end of the day (or week, or month), the numbers don't balance out, a flag is raised, and someone investigates it. And in many cases, there is a waiting period before you can access funds transferred.

Outside the US, people find this whole thing crazy, but that's how it is and it actually works well enough. My understanding is that banks are moving to a more modern system, but it's a slow process given how much is built around the current system.