Alternative (humanist) explanations - a) it feels disrespectful to howl past at 70 mph, when there are people hurt or at least having a seriously spoiled day; b) there might well be debris thrown into this carriageway, which will be much easier to avoid at 50 or 40 than it would at 70; c) other drivers will be thinking one or both of the above, or of course not concentrating because of having a good look, so it's either slow down or plough into them at 70 mph.
When the above happens on a busy road, the dynamics of the situation brings the traffic to a complete standstill half a mile up the road, after which everyone gets going to filter past at a sensible pace. You and I will keep a good lookout for the idiots, but they will be looking at what happens. And the OP is right: they are a damned nuisance.
Edit afterthought: am I allowed to write that in the Rant Room?
Last edited by ChrisH77; 22-10-16 at 20:03.