Hate to burst your bubble, but as an LEO I can tell you that officers pick and choose speed enforcement all the time. Some days one might write a violator for 5-10 over the speed limit, some days one might let a violator go for anything under 15 over.
Some officers write tickets for having a tag light or headlight out.
Personally When I catch people "parking" if I find them engaged in an act of sodomy, I charge Crimes Against Nature (A Felony) over Indecent Exposure (A Misdemeanor).
Has the local DA ever prosecuted any of these felony charges?
If you found a married couple "parking" and engaged in an act of sodomy, would you charge them with the felony?