Unofficially, though, they only want plastics 1 & 2 and very clean cardboard and paper, if even that. And the metal, but probably not the glass. The thing is that around here the same folks who handle the landfills also handle the recycling, and they will take whatever they can get for free (no money changes hands) if they think they can monetize it - a situation which seems to change on a daily basis. I suspect that an awful lot of what we think we "recycle" around here actually ends up in one of their landfills instead.
They do deals with big Chinese companies to send recyclables to china to be recycled. Three big problems with this:
1) the climate impact of actually shipping this stuff over seas is huge.
2) There is no oversight on how these companies behave, there has been numerous reports of them NOT recycling at all and many reports of slave labour being used to "sift" the rubbish
3) China is now clamping down on it, they no longer want the rubbish, many councils have no backup plan for this eventuality and yes its likely to head to infill.