Seriously.
There are two miles of un-gritted road before I get to a gritted/ploughed road, and most of the minor roads in Cumbria never see salt. I would imagine that's the same for most rural counties. So unless you never leave an A road, I would imagine that most people drive on untreated roads, unless they live on a bus route.
You need to remember that winter tyres are better below 12 degrees than summer tyres.So that's probably the majority of the year,
Yes you have to buy the tyres( say £200-240), but on the other hand your summer tyres will need changing less often. If you do 6 months turn around they'll last twice as long) If you get a cheap set of wheels(mine were £50) you can swap wheels/tyres yourself.
If you compare these extra costs ,offset by the extended length of your summer tyres, then compare that to the cost of one accident caused by slippy roads, then the outlay doesn't seem much.
I firmly believe that the government should make it law to change to Winter tyres, just like in many European countries.