"Bad guys"? I'm sorry, but that sort of simplistic two value judgment clouds understanding of actual threat and risk. There is literally almost nothing stopping people from blowing up/shooting down US aircraft if they wanted because TSA is wholly ineffective and incapable of performing their job: the fact it hasn't happened has *nothing* to do with TSA or DHS protecting people from Bad Guys (tm) and everything to do with the fact that the threat is over hyped and close to nil. The US will never admit that because they've spent the last ~50 years creating the Enemy Dictator of the Week for Americans to fear and now fear is the only thing they know.