Government employees check your ID before you get on a plane. The government tells us that's why nobody has taken an aircraft since 9-11, but that's a typical self-serving government lie.
How often do we read about people smuggling something onto an airplane to test the system? If a bunch of kids can sneak toy guns onto airplanes, terrorists can sneak real guns onto airplanes. Bad guys can get good IDs. It's so easy to get a fraudulent ID that Reader's Digest* had an article about people who couldn't drive bribing inspectors to get licenses to drive 18-wheelers.
Fake IDs are so easy to get that checking IDs does nothing for security. Government claiming credit is a lie, so why hasn't there been another hijacking? The reason nobody has hijacked an airliner since 9-11 is that the dynamic changed. It used to be that if someone kidnapped a plane full of passengers, the terrorists might kill 1 or 2 but most passengers would live. Now we're being kidnapped to ride shotgun on a suicide mission. It will take heavy weapons to take over a plane full of 150 people who have nothing to lose. Anybody who messes with a pilot will get mobbed.
Inspecting IDs is a waste of time and money, but it's ideal from the bureaucratic point of view because it doesn't solve the problem. If someone wants to take an airplane, it's simple to get weapons on board. The agency will say, "We asked for money and you wouldn't give us enough. We'll take care of it, but you'll have to double our budget." Bureaucracies have a motto, "Never solve the problem; there's more budget to be had from making it worse."
If we're serious about stopping terrorism, the solution is in the Second Amendment to the U.S. Constitution, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Terrorists can attack any time and place they choose. We can't hire enough cops to protect every vulnerable point. We put guards on planes, but so few that terrorists can pretty much ignore them.
What if we armed the people? Thousands of citizens learned how to use weapons in the military. A lot of them had security clearances. If we asked them to carry guns to protect us, they'd jump at it. They'd even pay for their own weapons and training.
I don't know how many armed citizens we'd have walking around, but we have a lot more potentially-armed civilians than we have sky marshals. If asking well-trained ex-military to fight terrorists isn't a good reason for a "well-regulated militia," I don't know what is. The entire program could be managed by the National Guard.
The bureaucracy would hate that. It wouldn't cost much money, it wouldn't create jobs, and it would solve the problem. That's death from the bureaucratic point of view.
After 9-11, Congress passed a law saying that licensed pilots could carry guns. That would work, but since it would solve the problem, bureaucrats dragged their feet putting licensing procedures in place. Bureaucrats always prefer expensive "solutions" which won't work to something cheap that will work.
* - Reader's Digest, July 2007, "License to Kill," p 37--39. In 2006, the U.S. Dept. of Transportation identified 15,000 "suspect" license holders in 27 states. p 37. The feds found that illegals can get driving skills certified for $500-$1,500. Given that the 9-11 team spent just over $1 million planning for 9-11, buying IDs is nothing.