I suspect it's not about protecting the people (your college stadium example), and that it is about protecting the expensive airplanes.
If I'm being charitable, it might also be about protecting the buildings that planes can crash into.
If I'm being charitable, it might also be about protecting the buildings that planes can crash into.
But sure, let's forget about morals for a second (lives lost and all that) and be very cold and cynical about the pricing. Still - reputational damage, political outcry, people suing the company/government for "failing to do even basic security checks like belts and shoes" - $100 million is nothing.