Solid wood cabinets are becoming very rare.
I still use plywood carcasses and wood frames.
I don't build a lot of cabinets, but i build customs.
The particle board is just too fragile for my taste.
Pricewise, P-board is cheaper, it's easier for the major manufacturers to handle and there's less waste for them.
A custom builder can use whatever you want, you pay for quality though, because the real wood requires much more work in the finishing.