That's a separate issue I don't support outside of situations where they can reasonably prove/show you crossed without alrady going through the search. Luckily, at least so far afaik, it hasn't really been deployed in the maximalist way that turns the whole country into that zone. It's a lot easier to justify near physical land borders like Canada and Mexico than it is if it's being used within 100 miles of very controlled impermiable borders like international airports. Has it been used outside of the land borders?