Recently these countries have blocked the import of the trash because it absolutely destroys these countries. The "recycling" companies buy in mountains of trash, pick out a few bits that are profitable and dump the rest somewhere. Currently only a tiny part of recyclables actually gets recycled or downcycled because the rest is cheaper to pull fresh resources out of the ground.

>> AFAIK we sell it to them

That implies there are other buyers who are happy to pay money to take it, doesn't it? That doesn't seem to be happening though:

https://qz.com/117151/us-states-banned-from-exporting-their-...

I suppose some countries agree to take the trash in return for some kind of economic favor from the US?

Yes, not only the western countries dump it in developing countries, they get money for it.