In the past five years there was one day when I couldn't cycle to work due to black ice covering most of the roads, and even that resolved itself in the afternoon. Snow just means you need a bit more dexterity than usual.
As for comfort; proper clothing means you are pretty much comfortable most of the time.
The ultimate irony of the point attempted to be made is that people don't drive when ice or snow cover on the road (or suck at it, take undue risks, fail to, and ram into curbs/cars/people).
What's more, in bad weather people (who have the option to choose between public transportation and their own vehicles) tend to choose cars more often because public transit has a habit of becoming increasingly unreliable, especially due to winter conditions, even though such conditions can be reasonably expected for 6 months a year.
I used to do 15+15 km bike ride to work and back almost every day for 9 months out of the year. Sadly I can't do that any more as I moved farther away from work.
There might be days of bad weather where other means of transportation is more convenient, but that's the case all year around.
For motorcycles/scooters the season is shorter because you can't get (affordable) insurance.
Citation needed, I know. There’s a relevant article about this phenomenon out there somewhere, if I can find it I’ll post a link.
I ride a fixed gear In winter, with the same tires I use in summer. A lot of people are on mountain bikes. Some people are on fatbikes, but that's overkill for basic commuting.
Sure, on rainy or super cold days it's not like it's as comfortable as a car but you'd have to pay me to drive a car around Paris or any big european city at rush hour.
The odd thing about this is how the biking paths around here (a city 60N) still remain relatively empty for a long time in the winter. It almost confuses me, but not really :-)
I know. I expected to get this kind of responses. It shows how little empathy this site has for other (older, overworked, with 3 kids, pregnant, ...) people that are just a little different than they are.
Saying "countries" is funny. It's varying wildly within a country, even a small one. E.g. my home city of Hradec Králové is built on a completely flat area with mild weather, so of course everyone bikes almost the whole year, but Prague is built on a series of steep hills and enjoys rougher weather, so while you see people biking here, most people don't.
Biking in the winter is fine too, as long as there's no snow (and the snow is usually only 1-2 months, depending on the location).
And some people do drive in the winter too (but that is harder and most don't).
Arguably many people seem to consider their car as a self-propelled living room, fully equipped with sofa and entertainment system.