The only thing that comes to mind is that climate is supposed to be mild in the UK, so maybe double glazing makes less sense than in colder countries? But it can get pretty cold in the UK...
My comment wasn't meant as a criticism of your comment.
A contributing factor is the popularity of rented accommodation, including council-owned houses, where the pressure to invest in double-glazing is less (as tenants are responsible for gas/elec bills, but landlords are responsible for capital-expenditures and improvements) - so there's not much incentive to upgrade windows in that case.
But all new houses I've seen built since the late-80s all tend to have double-gazed windows, the majority have white PVC framing, but I see wooden ones occasionally too. I've never seen white PVC window framing turn yellow - my parents had their windows converted around 1994 - now 23 years later the frames are still pristine white - and I'm not aware of any special treatment or care they require.
That said, public perception of double-glazing salesmen isn't the best - they were the butt of many a joke in the 80s and 90s, including Blur's Parklife video: https://www.youtube.com/watch?v=YSuHrTfcikU - though I never understood myself, perhaps because they were a commonplace sighting?
That... and even today they seem to capitalize on their public perception with intentionally gauche TV ads: https://www.youtube.com/watch?v=OgqJPd_YJtE
A friend of mine lives in a single-glazed 13-storey 1960s apartment block. It can be quite drafty. There's no way it will ever be refitted and I'd give it a couple of decades until its demolition.
The UK's housing stock is very old on average and some of it is in very poor condition.
Any data to back this up? Personally I find it a pretty rare sight to see windows that aren't double glazed and if I came across a property without them it's absurd enough I wouldn't move into it.
Well, I've talked to people and been to quite a few places in the UK, Scotland, etc. I know many people living in London, the UK and Scotland. We all agree. I'm pretty sure it's the same all over the UK
And for the rental prices that you pay here, it's pretty shameful the state of the houses, windows included.