The problem is that there is no money to be made from selling recycled styrofoam since it is competing with products that are themselves extremely cheap. If we imposed a high enough tax on the original product, then it would be cost effective. However we still have the trouble that we have to collect it, separate it out from other wastes in the waste stream, and so on.
So we could recycle styrofoam. But we don't because it is not cost effective to do so. So it is viewed as unrecyclable. And for that reason we have replaced it with things that are even less recyclable.
No wonder. Maybe volume is not the good metric to look at when comparing styrofoam to paper.
Styrofoam is insanely bulky. The same orders could be filled with a fraction of the volume of paper.
I had a friend whose father was a chemical engineer back in the 1980s who did a study on it. The cost per cubic yard to recycle styrofoam was insanely cheap. It was just that it required a specialized process that nobody implemented because creating more was also cheap. So it wasn't recycled, but it could have been.