The history of airport security is somewhat interesting. There wasn't a TSA for long time, and the hijackings/flying to Cuba got annoying, so metal detectors were added.
Everything else since then hasn't made much sense.
Interestingly, another approach that was seriously considered was to build a fake "Havana airport" in southern Florida and have the planes land there instead.
Yes. Six, possibly even six and a half, flights every five years.
The low rate of hijacking is due to the scarcity of people interested in doing it, not the difficulty. Same reason your house doesn't get burgled every day.
The history of airport security is somewhat interesting. There wasn't a TSA for long time, and the hijackings/flying to Cuba got annoying, so metal detectors were added.
Everything else since then hasn't made much sense.