[swewing]

When boarding an aircraft the information is still used to mark you as boarded in the airline's system.

This information is then checked when the flight closes to make sure that everyone who has checked in has actually boarded.

The scanners at TSA entry points might be a different story. I'm not sure if they're linked into the airline reservation's system, or if they just check the barcode to see if you have a valid flight for that day listed. I'm certainly not going to test this theory though!

Fortunately the country I live in (AU) allows anyone through domestic security check-points, so it's a non issue.