It is trivially easy for nation states, non-nation bad actors, etc. to use US payments. I'd guess that most of the financial scams targeting Americans rely on US-based mules and their American bank accounts.

Also, foreign nationals legally residing in the US can have access to US-based payments. There's no way when accepting a credit card payment from a US card issuer to ask whether the card holder is a natural born citizen versus Green Card holder, etc.

For peons sure. For anyone who is an actual security threat it would be easy. That is why this is either a) stupid or b) yet another lever to make it easier for this administration to incarcerate people.