I think it depends on measure, if im not mistaken, by weight arohnd 50% of microplastics are tire dust.
You only think that way because the material for a tire is all in one place and easy to see.
Paint on the other hand is effectively invisible when we ‘inventory’ a space mentally.
So a tire in the middle of your living room seems like a lot of rubber but all the paint over every inch of the wall in the same room doesnt, even if the room is big enough for the paint to fill the volume of the tire.