I sometimes feel like the only one who does. Quite often I'll be driving down a 20 road, at 20, unless I have to slow for meeting traffic or very tight roads, but i don't even go 21. I go by my sat nav speed, which shows as about 22 mph on my car.
Most days I will see a car in my rear view mirror quite a way back, then suddenly it's right behind me which means they were doing over 20 in order to catch me up so quickly.
Often I let them pass as I hate being tailgated, and they absolutely wizz down the road. I think they think because there aren't cameras on that road they'll be fine- but it only takes a person running out into the road or a police car in the area.
It's just so common, I know 20 is slow but they think it doesn't apply to them, tailgating should be illegal. I'm just astonished how many people routinely speed and seem to get away with it.