Why do police act as if they are above everyone?

I just had a trio of cops stroll into my shop, where I have a soft drink fountain, coffee, and other things(c-store). The three police officers come in, stand beside the fountain, and BS for almost half an hour about this perp, and that perp. After drinking my sodas, and refilling them, they walked out, and before the third one walked out, I said "are you going to pay for that?", he chuckled, and walked out. WHAT IS THE DEAL HERE!!! I AM TRYING TO MAKE A LIVING HERE, WHAT GIVES THEM THE RIGHT TO JUST WALK IN, LOITER, AND STEAL MY SODA!!!!!