Actually there is. Certain plastics can be easily segregated and can be turned into "plastic wood". It had comparable strength to 2x4's, 4x4', etc. but was a little more difficult to work with. But these days, many carpenters are using screws instead of nails anyways. Plastic sawdust, probably too hard to clean up properly.

Back in my recycling board days, plastic wood was about twice the cost of real wood. Maybe the economics have changed.

But governments were doing very little to move the concept of plastic wood forwards. So too was "free enterprise."

Very little work on other plastics. I cringe every time I buy a loaf of bread--and we cannot use that plastic bag somewhere else.