Mondo, perhaps. They use a lot of recycled rubber.

real ballers play on concrete

Tartan Track is Cradle 2 Cradle certified; you might be able to use that for a basketball surface.

therefore real ballers must have severe knee problems...

Can't you just paint the concrete to make it green? ;)

I played a LOT of ball outdoors in college/ grad school. Way too much mileage on the feet and knees.

I wish they had outdoor rubber surfaces back then bc I'm paying for it now.

I played once on a very strange reconstituted rubber court. It was prob just finely shredded tires or something. You could even pick the rubber off the playing surface but it made it much more cushiony and was a surprisingly good playing surface.