You don’t want to use brick in a seismic zone, reinforced concrete is overkill for a 2 storey house, and steel frame is not just overkill but also uses sticks and cardboard for nonstructural components.

As far as I can tell, almost every building in western USA that isn’t tall is wood frame construction.

https://en.wikipedia.org/wiki/Framing_(construction)

There's a growing concept of 'mid-rise' woodframe construction as well due to how the codes are written.

Yep, first (ground) floor is concrete with a slab "roof" and then a four-story stick-framed building constructed above that. Ground floor is either retail or parking. I guess they pass fire code but they look like tinderboxes to me.

Isn't this the case for most of the US, not just the West Coast?

We do not frame our houses with stones in the US. It’s not cardboard it’s OSB[1] (Oriented Strand Board). The US and Canada make most of it.

[1] https://en.wikipedia.org/wiki/Oriented_strand_board

Why don't they use reinforced concrete since they're in an earthquake and fire zone? This wood seems so temporary.

The numbers don't pan out until for buildings with fewer than 5 floors or so. I don't know the street, but this will almost certainly be a 3 story house, max.

Lots of historic reasons for why Canada and the USA build with wood, but beyond that and going forward, I expect we're going to see even more of a pivot toward wood buildings as both countries try to meet their climate goals. Concrete is a big CO2 emitter while wood is CO2 storage.

I wonder how brick adds up?

Hm. No idea. Probably the worst material for the earthquake zone cities on the west coast tho.