The problem is these days there is all stick and no carrot when it comes to speed limits.
The hard of thinking parrot the limit, as if 1 mph under the limit is safe, whereas 1 mph over it is unsafe.
The reality is that it is a sliding scale, not an absolute one.
I am all for 20 mph limits around urban areas. They make a lot of sense where I am yet the limits are still 30 mph.
Yet I think 70 mph is too low a limit for many main roads and we would be better off having a french style which varies depending on weather conditions (this of course makes the limit more interpretable, but maybe does highlight the fact that people should be driving to the conditions more rather than the limit and actually thinking about the speed they choose, which is the whole point).
You only have to look at the number of cars exceeding the limit on the motorway to realise a significant proportion of the population feel the same way.
Still, disagreeing with and maybe exceeding the limit and tailgating are to me two very separate things. I will not tailgate because I believe it's too dangerous, whereas exceeding the limit I think under certain circumstances can be fine.
I don't believe that someone tailgating at under the limit is driving in a safe way, although technically they are under the limit (they may get prosecuted for driving recklessly or with undue attention if an accident is caused).
If the government wants to reduce the accidents on major roads probably the one thing it could try to do is reduce the incidence of tailgating rather than focus on speeding. Of course doing this is harder, which is why to date they haven't done anything about it. But the technology exists.