It's drivers that are the problem
Actually, I would say that the volume of traffic is the biggest issue. Don't believe it's all drivers' fault. A few years ago I was in Farnborough when it snowed - there's a humped railway bridge that is on a critical route (the town is chopped in two or three by railways) and it was completely slick ice on both sides. No getting over that without a big run-up and some gunning it. Which isn't easy or safe in heavy traffic. So all the traffic that would've gone that way had to back track and go a different route.
Lots of other factors too. My wife's from Wisconsin where it snows a lot. People get around, but they all have winter tyres, the place is flat as a pancake, it's not busy, and the streets are in a grid pattern so if one gets blocked or is not ploughed you can go a different way. They're also wide, with tons of space to manoevre and get ploughs down.
However, despite all that, there's still traffic problems when they get decent snowfall. They just expect it, rather than whine about it and dissect it endlessly on internet forums.