It... already does. You can get a warrant for whatever evidence you need already, no need for any new legislation. The constitutional requirement is for judicial supervision, and that's been pretty solid (not perfect, but good) for almost three centuries now.

I'm just saying that there is no "right to financial privacy" anywhere. You have a general right to privacy as granted by the fourth amendment. And courts take that seriously. But it's not absolute and the government is allowed to unmask things for law enforcement.