UK Elf & Safety is indeed ridiculous at times.
However, it all comes down to money... As airports are privately operated, they are free to choose the limit of what kind of disruption is economically viable, just as the airlines do. How many fail-operational B737NGs operate in Africa or Australia? Probably zero, because it makes exactly zero economical sense to pay a lot of money for the one time a year (or decade) you will need it. Or how many Cat 3B installations are there in those parts of the world?
I really don't see any sense in buying equipment to ensure Scandinavia-style winter readiness in UK, which gets 1cm of snow for 3 days a year.