Why are TSA agents such assholes?

[NuclearEnergy]

Seems they are bigger assholes in the more larger airports. For instance, we went to the Dominican Republic and we connected to our return flight to Phoenix in Miami. When we got off the plane in Miami we literally had to walk about 1 mile to "passport control". We then had to go through another wave of customs. THEN...we had to go through security again because customs takes you outside of the secure area. So as we are going through security one of the TSA people yelled at me treating me like I'm some kind of terrorist because I put my shoes on my laptop as it was going through the scanner. (I know it has to be by itself, but I've done it that way countless times) One of them also yelled at my Dad telling him he should know all this because they have been doing certain things for the last 10 years. I understand it's a difficult job and they're not going to be all smiles, but your tone is the most important thing. 

I personally think TSA is totally useless and just an illusion of security. Privatizing it would be better in my opinion.