a cultural question...

I've noticed several times references in fiction about people airing out their house once it got warmer that made it sound as if Americans don't open their windows in winter to let fresh air in. Like as if they don't air their house if it's freezing outside.

Is that true? Is it a central air conditioning thing where you don't really need windows to get fresh air, and shouldn't disrupt climate control or something like that? Because otherwise I can't imagine not to open my windows at least twice a day for a little while. Admittedly it's rarely extremely cold here, but this winter we had days when the daytime high was below -10°C and I still aired out my place briefly.

Here you are even required to do so in rental agreements because otherwise you get problems with moisture buildup and such.