Piling on a bit: the TSA is legally forbidden to conduct general-purpose "looking for anything illegal" searches. The only way they are able to stay even slightly on the correct side of the Fourth Amendment is by conducting administrative searches for narrowly-defined lists of items which pose a direct threat to aircraft/traveler security.

General-purpose searches for anything that might happen to be illegal require probable cause or a warrant for each individual person to be searched, which is something not even the most desperate-to-get-elected "secure the homeland" politician could make happen.