It would probably help to label them better, I have lost count of the number of times I have seen plastic bottles in the (green) glass bin and glass bottles in the ( yellow) containers bin, primarily intended for plastic bottles and aluminium cans, and as for the (blue) paper/cardboard bins - well, anything can be found in there!
I was particularly annoyed last year to find a recently positioned orange bin - for waste cooking oils - stuffed full of empty plastic bottles instead. Are people really that dense??