A tax can be collected without a "presumption of innocence", but it does require Congressional action. Also, Trump today said he was going to bar remittances, not tax them. Big difference.
The barring on remittances was something Trump's memo said would apply to those who couldn't prove legal residence. But as virtually every employer knows, getting bogus documentation is easy, as is simply giving the money to a lawful resident surrogate.
It sounds like a great idea, but it wouldn't work. The solutions that really would work require Congress, and the best of those is the imposition of a tax on remittances.
See I think it will work, who is going to stop him? Congress? The court has no means of enforcement. I see it this way, if you play Their Game, you LOSE no matter what. Someone has to start mixing it up and Change the Game. Then firmly tell them to Go Pound Sand.