My encounter with cops in the United States

Are they really to help the public? This is the question that rises in my mind immediately when I see a cop. I feel a cop in the United states is only there to exhibit his authority. If he is really there to help people out why is it that no one feels comfortable to talk to him. Its always scary to encounter a cop. Puts his car on the way, glows his irritatingly bright lights even in the darkest hour of the night, puts them on for a long 30 minutes even when he has to talk to the so called culprit for just a few minutes. 
One day, I was standing in the MV office in a long queue. There was only one guy working though there were five counters. This cop guy walks in, looks around, I hope that he's going to help the confused people in the room, instead he takes out his phone, starts having a nice chat, probably with his girlfriend describing how lousily he's having fun in his job. Why doesn't he go out and put a call to the other guys in the counters who have gone for lunch more than 2 hours ago.

There were times when I was stopped on the road by a cop. The first one was when I was talking on a phone while driving, that was the only time I forgot my blue-tooth at my home. I was also late to office so I called up my company to inform them that I am going to be late. This guy comes behind me, glows his lights and stops me. He won't listen to even one of my words. Gives me a ticket and says have a good day. How dumb of him! how would I have a good day? The second guy catches me when I was speeding. I agree that its' a mistake. He asks me what I do and when I say him I am a Solar research engineer he says he doesn't have any idea what is Solar. Oh common dude, which world are you living in. Who in this present day be a guy who doesn't know what solar means. I guess there was a competition that was held to elect the dumbest of the people in the United states and the guys who came first were selected to be cops.