How interesting.
In all seriousness you could make a home from almost anything else and it would end up being more fire resistant. The flammability of your average US suburb has to rank somewhere near 1944 Tokyo.
The single family code is optimized for cost, cheapness, ease, and speed. The multi-unit code is optimized for expense, difficulty, and making sure as little gets built as possible.
That means that even though the US suffers far more deaths from structure fires than the rest of the world, common-sense multi-unit designs like single-staircase that are present in safer countries are illegal in nearly all of the US.
It could be semi-random, based on a lot of events, motivations, etc., that occurred or didn’t occur by chance.
But I think that even without the motivations being written out, it's pretty clear in the nature of their differences.
Funfact: in large parts of Central Europe (ex austrohungary), wooden homes were banned after a series of large fires in the 1800’s. Brick was considered to give people a better chance.
Although it turns out that’s really bad for earthquakes …
I've seen videos of houses being built in the US and I'm not sure my local construction workers would believe it if I show it to them.
The old houses are made with rocks and the new ones with concrete. The wood is usually just a decoration on top.