I don't know how serious is USPS, but in my country the post office doesn't check if the signature looks the same for example.

Banks face and handle fraud on a much higher level, and have a much better training in identificacion.

My signatures never look the same. Signatures aren't a good judge of authenticity.

My point is that a bad actor would have to show up in person and lie to a federal entity. It's not that they won't get away with it- it's that they cannot hide on the other side of the globe.