#Plastics that say # 5 PP+ and/or “Cryovac” are very hard to recycle. If you pay for a TerraCycle box (my neighbors and I do), you can put them in there, but … whew.
That’s often to-go food containers, for instance. Anything where different kinds of plastics are melted together = much more work to recycle/reuse. (Again, it’s not anyone’s individual fault, but we can all try do what we can, so check your plastics for “cryovac” & try to avoid if possible.)