Is it normal the police let me get away with drinking and driving?

I use my better judgment and do not drink so much I am wasted but often I will drink about 2-3 pitchers and drive home from the bar. I'm about 235lbs and have a high tolerance so it doesn't get me too drunk. If I feel too drunk I will sleep it off in my car. Anyways there have been 3 occasions I have been pulled over coming home from the bar for speeding where the officer could smell that I've been drinking and I am always honest with them. They have me do the sobriety tests such as walking in a straight line and standing one foot which I always pass and then give me the breathalyzer which I am probably a bit over the legal limit of .08, but they let me go anyways. I think this may be because I call 911 about once a month on average to report something like meth labs, people driving drunk to where its obvious, kids diving off the local bridge where everyone dies, and other things that cause danger. I wonder if when they go to their computer they see that I report these things so they see me as a good citizen. Now I don't need any lectures about me being a hypocrite. Like I said, I only drink and drive if I am not so intoxicated that I cannot pass the tests besides the breathalyzer. Is it normal that the police do not arrest me for this?