I think a big source of contention is a failure to clarify what type of road requires change, leading to frustration from people believe someone wants to drop t

I think a big source of contention is a failure to clarify what type of road requires change, leading to frustration from people believe someone wants to drop their suburban 45mph artery road with no driveway access to 20, when the other person is just talking about an collector in some dense urban zone. Not to say those people may have a point however; speed cameras always seem to have a mysterious way of appearing on split expressways with a new speed limit rather than the avenue near the school zone that actually requires it.