YUROP

Most litter isn't there because the original owner accidentally lost it, it's thrown out on purpose. You're right with the old system not all plastic bottles were thrown out with the cap removed, but some were. And in general, cleaning up the big part is easier than cleaning up the small part. I don't know the science of how big a difference it makes, I don't know if it is worth the inconvenience but even though your logic sounds very logical,stray bottle caps was big enough a problem for the eu to want to find a solution.