I hear you. But to my mind, it's no different from any other profession. I'm in the computer biz and if somebody else in the same field asks me for a favor I'm likely to do it for them, just as a professional courtesy. Oh, I know it's not exactly the same... But that's what's going on.
And, again, I find myself in agreement with Mr Boudrie: Be polite, fess up if you know you did whatever minor thing it is, and you'll almost certainly get a pass.
i ran a stop sign entering a rotary a while back. Just looked to my left and kept on going. The problem? There was a cop on my right looking for this exact behavior. He stopped me and I said "Bet you're stopping me cuz I didn't stop at that stop sign,eh?" He said "Did you know it was there?" "Yes," I answered, "but I looked left and nobody was coming, so I just went on through." He laughed and said "you're the first person who hasn't argued with me, and tried to tell me that they DID stop, all day. Here's your license. Just please stop at that stop sign next time."