Unfortunately that boat sailed in the 1970's with "California Bankers Association v. Shultz" which upheld the requirement of banks to report large transactions

Unfortunately that boat sailed in the 1970's with "California Bankers Association v. Shultz" which upheld the requirement of banks to report large transactions to the federal government in order to engage in surveillance against organized crime. I think that decision more than any other has been responsible for the collapse of protections against surveillance. Indeed in a remarkably prescient dissent, Justice Douglass more or less described where this was leading by describing in accurate detail some of the current anti-drug laws that have been tacked onto the USAPATRIOT Act as it has come up for renewal.... There is hope. The logic of Alito (joined by all liberal justices, except Sotomayor) and Sotomayor (who joined the conservative justices, but also endorsed Alito's logic) in Jones v. United States is quite incompatible with that earlier decision and it provides some hope that lower courts will say "oh there are five votes for tightening things up" and start to do so.