Even glass has become questionable in terms of recycling economics[0] based on current fees, partially because Americans generally fail to clean the containers properly.
"It's cheaper to dump it in a landfill" is frankly, a lame approach that ignores the environmental costs and short-sightedness of creating more landfills. Do you want to live on a landfill, or next to one? They're basically a toxic waste dump.
The obvious answer is to do what other countries do: charge a lot for disposal of non-recycleable/non-compostable garbage, charge much less for recycling properly (and that includes cleaning and sorting), and use the fees from the garbage to subsidize the cost of recycling. This results in 1) less waste in landfills 2) more recycling 3) less pollution and 4) less use of non-renewable resources.
[0] http://www.waste360.com/glass/focusing-economics-glass-recyc...