That's really interesting! We do have some signs on some tracks, but rarely on mountains - usually just on the lower levels. I've never seen avalanche signs, probably because most of our mountains are not high enough to have snow year-round, so the avalanche risk areas change frequently.
I've never seen a cornice warning sign.
Also, this kind of thing can be a controversial subject in Scotland. A couple of months ago I was walking on a mountain after heavy rainfall, and part of a steep path seemed to be dangerously eroded. I walked over it, but I later met a couple who told me they had turned back, as they thought it was too dangerous.
Later on, I mentioned it on a Facebook group for hillwalkers, and a few people laughed at my comments and posted "nanny state" memes, even though I was only mentioning it, to warn people, not demanding action or anything!
I also mentioned it by email to a mountaineering group, and they were really helpful.