I don't have a reference, but I believe coffee cups are assumed to be recyclable even though actually, and in most part due to the polyethylene-lined inside, they are not.
And here I am thinking it was a wax lining. Why would you a plastic lining for something you put hot liquid in, which would cause leeching? (Not that was doesn't have issues, aka melting)
Try putting some hot water in a "cup" you make from paper and you may find that the thin plastic barrier makes some functional sense.
I agree however, that I'd rather just use re-usable glass or metal cup (with a handle or suitable insulated wrappping) and avoid the potential for hot liquids leaching things out of plastic!