Why are airport lines still a thing?

Airports (or maybe the TSA) should face giant fees if passengers have to wait in line for more than 5 minutes to get through security. Here one of the two screening lines is closed because they didn’t have enough people to staff it I asked the security rep and she said that they were fully staffed, but those people were needed elsewhere.

Im guessing these machines cost <$200/hour to operate including salary of the operators. If operating it would save 300 people 15 minutes every hour, choosing not to do so is valuing everyone’s time at less than $3 an hour, which I find unconscionable. Airport lines are one of those things that we take as a fact of life, but they could easily be eliminated in most situations if we forced these monopolies to add a bit of slack into the system.