Originally Posted by FlyingHoustonian

But I am saying, I fly to Merida for business very often, and at MID it is not done at the gate, it is done in the terminal at a formal Federally manned immigration booth where they can, and sometimes do, ask questions on exit; thus my question above. In fact, my last trip to MEX, granted some time ago, and VER several weeks ago had the same Federal immigration officials at manned desks taking the cards well before the gate.

From what was said above, it seems like it is being promoted as always happening at the gate or by airline personnel which is not ('always') correct.