Ice is not problem with studded tires. And isn't snow is usually plowed from the roads so cars or bikes could pass?
The bike paths are a bit less busy but basically nobody changes their behavior except to go slower around the icy corners.
This is in Netherlands
Better comment:
I'd think that many people still commuting, doesn't erase the fact that cargo bikes (the thread topic) don't do well in those conditions.
And a critical factor is, hills. I live in a countryside that alternates between flatlands and all-hills. The towns are all around rivers (the pioneers needed water) and built close to them, and it's very hilly around rivers.
So here our experience is different from, say, the flattest country on earth.
It really depends on how well the roads are maintained, this winter they were quite good at clearing the snow in my city, so it wasn't much of an issue.
I took the bus when it got to -30, though. Or, as they reported it then, a wind chill of 2400 watts per square meter.
In some places there's Winter, not just the pause between autumn and spring.