Because back in the '60s, the government plucked the number 70 out of thin air and arbitrarily decided that that was the maximum speed it was possible to drive on a motorway or dual carriageway without killing someone. Since then, cars have become more safe, with shorter stopping distances, airbags, bonnets shaped so as to not shatter every bone in a pedestrian's body, you-name-it. The speed limit is still 70.
That said, one does have to question the wisdom of concentrating on filming a speedo while hurtling down the road at OMFG miles per hour. And then uploading the video to the Internet. And listening to such crap music. I'm not going to lose much sleep at the thought of this gentleman not being able to drive for a while.
Actually, the number was picked out of fuel economy concerns, not safety
But with respect to safety, you're right... a modern car, especially something like a GTR as this guy filmed himself driving, with modern rubber and ABS... can stop from 100-0 in a shorter time/distance than a 1960s car could stop from 70-0.
On the other hand, like you mention, this guy - knowing the speed limits and potentials for punishment - was a complete and utter idiot to film himself driving like this. His disqualification, I couldn't give two hoots about, although 10 years seems somewhat excessive.
I can't get my head around how some **** of a judge has taken away this mans freedom for over 2 years and stuck him in the same cage as people who murder and rape...


True.
UK should adjust speed limits for Dual carriage ways and motorways for sure but both a wet and dry speed limit.
Wet: 75mph
Dry: 95mph
At the same actively fine and issue points for those who sit in the outside holding others up and also those who tailgate.
Perfectly safe speeds in modern road worthy cars and of course you don't have to drive at the limit, extreme weather then of course much slower, just common sense really.
That seems some-what appropriate.
Although I would remove any dry maximum limit where the road suits it, like they do in Germany.
A wet maximum limit should be strictly enforced, however, as I've seen some real stupidity in those conditions...
What we need to improve upon is driver education... and re-education... we have people on the roads who learnt a different way of driving 40 years ago from what is acceptable today.