The reason they can keep doing it and no one really gives a shit is because once you explain to Joe Schmoe that cutting program X or agency Y's budget means he or his cousin or his drinking buddy could lose their job, well Joe can rationalize keeping that program.
Americans all want pork cut everywhere except their home district. We are short sighted, have short memories, and aren't willing to endure short term discomfort in the pursuit of long term prosperity.
Anyone candidate that would be for cutting this kind of corporate welfare isn't viable on a national ticket. Eisenhower was right about this all by the way.