Indeed, but those are the ones who make effort. A lot of people can't be arsed and just chuck recyclable stuff in the normal domestic rubbish bin..
Even the skips at the Viridor sites are abused. The one that should contain soil or rubble is usually contimainated with ceramic tiles, old bogs, stuff that should be in there.
Ditto the timber skip. All manner of junk that clearly cannot go through a chipper gets chucked in there.