First shoes in this context is outdoor shoes, that doesn’t mean being barefoot.
Second northern locations tend to have properly insulated and heated indoors, rugs, possibly floor heating, … when the cold is common it’s easier to spend more on heating and comfort. For instance in Japan central heating is only common in Hokkaido, maybe also Aomori.
(My responses are US-centric, since that's where I live)
> that doesn’t mean being barefoot.
It does if you're at someone else's place. or in your socks, which is roughly the same.
> northern locations tend to have properly insulated and heated indoors, rugs, possibly floor heating
That is far from the norm in my part of the US.
Don't get me wrong, if I'm a guest and asked to remove my shoes, of course I do! And without comment. But it does make for uncomfortably cold feet in the winter.