Another brilliant idea!!! That way, the TSA gains the right to search vehicles too. And people not flying. And think, they would be just like Stasi checkpoints! Mirrors on wheels to look under cars and everything.
Then think about the backups it would cause, and the extra staffing required. You would be doing 3x the searches when you include passengers of vehicles not flying and the cars - under the hoods, in the trunks. Think of all the contraband they would collect too.
Of course, this will not do anything to stop terrorism. The only thing that will stop terrorism is a mooselimb ban. Leftist are currently fellow travelers with mooselimbs so that is completely off the table.
They tried that after 9/11. It didn't last very long. (Actually, that may have been before they were called TSA).