In warm and dry parts of the world with good roads. You try biking in Toronto in the winter! Some people also understand that roads are dangerous, and being hit by a car when you’re on a bike is very bad news.
All you need are good roads. Bicycling in the winter in Helsinki or – even further north – Oulu is completely mainstream. People know how to dress for the outdoors, and as long as the bike lanes are cleared of snow, cycling is not viewed as the major inconvenience that people in warmer countries expect it to be.
Needless to say, this creates a host of issues you won’t find in Helsinki, where 1.2m of Finland’s 5m inhabitants live. A bunch of very similar people living in the equivalent of one American state or small Canadian province, speaking the same language and sharing the same culture and weather can make roads and cycling a priority. Good luck scaling that.
We are talking about one city; no one is suggesting that Canada’s rural areas – which is the only place it would be relevant to bring up distance or low population density like you did – need bike lanes, too.
There is a "National Cycle Network" of cyclepaths and roads that are exceptionally well-suited to cycling (low traffic etc.), and it is signposted well.
(But, again, I hadn't noticed any of this until after I got the bike).
Some people understand that cars are dangerous, and would see the risk of killing people with your car as a downside to using a car.
The parent specifically mentioned 'it doesn't go fast enough to be a danger to anyone' as an advantage for the bike.
But I didn't even know they existed until after I got the bike and started planning routes for journeys.
Even if the cycling infrastructure near you is unsuitable, there are still lots of people in places that do have good cycling infrastructure but either don't realise it or just haven't tried it.
Those people should strongly consider trying out an ebike!