Two recent events at airport security checkpoints in the U.S. reveal a serious lesson about public policy and government largesse.

At LAX’s Terminal 3 on November 1, a deranged gunman shot and killed a TSA employee at the checkpoint and wounded five others before being stopped by law enforcement.

A week later, at Seattle-Tacoma International Airport, a seemingly intoxicated man ran through a checkpoint; then onto the tarmac; and, finally, broke into a parked aircraft before his arrest.

Both of these cases demonstrate that the focus for aviation security remains much more so on keeping bad things, rather than bad people, away from air transport.

Airport security checkpoints focus almost exclusively on the things that travelers carry.

In the wake of 9/11, airports across the nation were re-configured to create more room for expansive checkpoints.

The plan was to keep prohibitive items like screwdrivers and box cutters off planes.

The federalization of airport security under the guise of the TSA was the fulfillment of that objective: with more than 50,000 transportation security officers deployed to search for things that could cause harm.

Over time- to its credit- the TSA has finally realized that such an approach is a tremendous waste of effort and money; and, doesn’t really make things any more secure.

The threats are human, not things.

Nevertheless, more than 12 years after 9/11, we remain burdened with a system that still focuses less on the bad guys and more on their possible weapons.

Despite new initiatives and directives, the wrong approach remains in place.

The lesson here is that once a public policy is implemented and momentum begins to take over, it is excruciatingly difficult to change course.

In the world of public policy, once critical mass is reached, influencing events becomes next to impossible.