Just to be a pedant, and because this fact tends to surprise people, asphalt is concrete.

Concrete is a generally defined as any mineral aggregate (so rocks and stones) mixed with a binder (normally cement, but bitumen in the case of asphalt).

As for why roads are normally made out of “normal” concrete, it’s very expensive to build roads like that. Pavements are cheaper to build out of concrete because they only carry the weight of pedestrians, not lots of rolling vehicles. You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension. Asphalt concrete cheats by being flexible, so minor imperfections in the surface or sub-base don’t become sources of critical failures (although they can become pot holes). Asphalt is also cheaper and easier to patch repair, but doesn’t last as long as proper cement road surfaces.

https://en.wikipedia.org/wiki/Asphalt_concrete

Huge temperature swings is a big part. Most people don't realize how cold it can get in the desert at night.

There's a lot of protectionism around asphalt maintenance.

I knew a city manager that got a city out of a major projected shortfall, without cutting any services, by investing in redicing long-term expenses.

He was celebrated for it, then fired, because the asphalt company that lost its contract had more political sway than the parks and recreation or public education departments that he fought for.

Cost.