This seems to be a regular occurrence on roads that were once national speed limit and are now peppered with 50mph limits.
There are a couple of reasons they've been downgraded.
Speed limits aren't just about road safety. It's also about quality of life. I used to walk the dog readily along one stretch of straight "30" limited road, but I'm wary these days with all the traffic.
No-one's perfect as Howard said, but it makes even me cringe when some donkey driver flies past at 40 plus..
Oddly enough, the big boys are usually very considerate. The noise of an empty bulker as it jolts is massive, though.
The blanket 50 restrictions have been brought in to slow everyone down, which of course, makes it easier to camera enforce as it's statute that way and not un-restricted..
So as a pedestrian, it's a Hooray. As a driver/rider, it's just not on.
We're a hypocritical bunch, aren't we..?