This is just for the US North East. Football and basketballs fields are never shared because basketball fields are always paved.

Thanks! It would probably work well for parking lots, but there are a horrifying number of them. I don’t think the OSM community would tolerate such a large import.

You don't have to do an import, you could just have a MapRoulette challenge. Or some sort of JOSM todo plugin, so people could whiz from one to the next