Something could be spelled out better here. If police traced back to a return address put on a piece of mail by the person they intended to find, what tells them the person isn’t holed up there with the tenant? Unless due diligence, of course, finds multiple pointers to the person at some different address, and I would fault police for not exercising that kind of due diligence if such records were within the detectives’ scope. It’s for a reason they’re called detectives. They’re supposed to detect things, not go wild.
So, they do without the warrant and use the address from some other source.
It's stupid of course, but there are still people alive who were involved in a Mail Cover operation for Richard Nixon who can tell you that in the long run even that warrant doesn't protect you from the druggies, Commies and assorted POS in the news media who protect them.
The Leftwingtards have been 100% responsible for every bad raid in modern American history.