Yes, "developing" countries have more litter, but they are also less "developed" -- by which we really mean, the land has not all been converted to farms and cities and industrial buildings and pavement.

Britain is not Mordor, but the shortage of trees and animals is real. Too much of it is an empty green lawn.

Whereas really it should be a temperate rainforest, fuelled by the Gulf Stream. It is a wet, lush, and fertile place. It just needs to regrow.