Maybe a bunch of people just don't agree with your position. (If they're idling and I report them, I'm a snitch. If I don't, I get to breathe the pollution. Why is snitching worse than poisoning people in your city? Why should the snitch be the bad guy in that situation, rather than the polluter?)
False dichotomy. Both the snitch and the polluter are bad guys.
If you want an example of widespread application of this idea in a society, look at China. I rest my case.