Makes you wonder how they manage in Scandinavia, Siberia and Northern China with a much higer snowfall than we will ever get. Their trains still get through, and often on time yet in Blighty the slight suggestion of snow and everyone panics and the network closes down!
Let's try the basic stuff, like it will inevitably snow heavily there every winter, so it makes sense to buy lots of kit to deal with it anyway, or you design for it, like raised third rails with snow covers and bottom contact current collectors on metros. Even then things go wrong. A very heavy snowfall around Oslo effectively shut down their metro for several hours one day a couple of years ago, despite the raised conductor rails.
Our climate is different, so we always try to wing it - it's not just the railways here that do this - Heathrow airport ring any bells?
Nor, outside the very biggest cities, are any of these countries running train services at frequencies that in any way resemble those that apply in much of this country. Less scope for things to go wrong and fewer trains to focus on keeping on the move when things do get difficult.
Top contact third rail is pretty useless in deep snow, so no wonder operators south of London are taking prudent precautions. If you try to run a full service and things start to get out of place, with trains and crews in the wrong places, the whole mess in such situations just, er, snowballs. If you have a contingency plan, you have fewer trains to run and can have the crews who would otherwise be on a train available at strategic points to step in if someone else gets stuck on a late-running train/can't get to work.
Even though FGW and Network Rail have contingency plans if there are problems between Reading and Paddington, even these have a tendency to fall apart, without any snow to add to the fun.