What percentage of American communities do you think the police force or council would do either of those things on the basis of a request? In Oakland it took years after multiple fatalities at crosswalks for there to be enforcement and road works.
As much as I dislike the survelience aspects, police operated red-light and speed cameras are already a thing. An app isn't going to fix the problem that your police don't care.
What percentage of communities are rich suburbs that have more money and staff than they really have a use for.
And IMO just covering that small % of communities would satisfy 99% of people making these requests.