We have laws that clearly state the criteria for being disqualified from owning a gun, and laws that require licensed dealers to perform a background check to ensure that a potential purchaser passes based on that criteria.
The system being proposed here would be able to deny boarding to a passenger who fails an arbitrary and completely unknown set of criteria, based on no laws and (most likely) violating existing law.
Actually we don't have clearly defined criteria, see red flag laws.
But regardless, even with clearly defined criteria, people get through that shouldn't. So going back to the original comment, if the system isn't 100% perfect, does that mean we should just not do it?
The system being proposed here would be able to deny boarding to a passenger who fails an arbitrary and completely unknown set of criteria, based on no laws and (most likely) violating existing law.
Do you see the difference?