Phrased like that, it's indeed problematic. But you should keep in mind that speeding is
1. A safety hazard
2. Causes high noise pollution
3. Measurably increases air pollution
Under these circumstances I feel like a citizen driven enforcement for the law is not quite bad as you are portraying it. I would even call it apploudable, because they increase the quantity of life for everyone in their neighborhood.
The problem here is the anonymity for the tipster. Like if you can't defend your actions by putting your name to them are they actions worth taking?
The guy who reports one person for driving 100mph over the limit can and ought to sleep soundly knowing society more or less agrees with his actions.
The guy who reports 100 people for going 1mph over the limit ought to be be worried. His actions are not something society generally thinks is a good thing.