[BrenBarn]

Other commenters already mentioned that the current situation in the US shows how fragile this "ironclad" norm is. Aside from that, though, the fourth amendment wouldn't necessarily prevent a law that requires companies to scan the data and creates certain liabilities if they don't. The weakness in the US's version of such "rights" is that none of them are actually guarantee that any individual rights are to be protected against all comers; they restrict the government from doing certain things but allow private actors to do those same things.