TSA checks IDs -- any valid IDs -- to let you in the secure area.
> If you were to arrive at your destination and be turned away at the border, they would be required to fly you back to your country of origin
If a border agent denies you entry, even for a reason the airline could not have foreseen, they are required to fly you back? Does that also mean that an airline is only able to offer flights between countries (A,B) if it also offers them between (B,A)? And is there some maximum time allowed between those flights, e.g. an airline can only fly into a country if it also offers a flight back to the same country within twelve hours?
I seem to remember reading something about countries putting denied entries on a flight back, by effectively loaning money to for the ticket… not sure how they collect on it though.