If you set your cruise control to 20 mph in a restricted zone you very soon get a lot of people very close up behind you looking very angry.
Many of them, I dare say, live in those areas and were the ones who pushed for the limit in the first place.
I get that in a 30 zone (even measuring speed with a GPS)!
I can think of at least one village where there was local pressure to install a camera for road safety purposes because the villagers were fed up with non village traffic breaking the limit. The majority caught over the limit, some 70% + in the first few months, turned out to be villagers...