Tip O’Neill, the long time Speaker of the U.S. House, was famous for saying “All politics is local”. The same can be said for recycling plastics: All plastics recycling is local. The plastics that are recycled in my community – and the amount of sorting required by the consumer – will be different than in other communities. There are no state or national regulations on this matter. Even within a given metropolitan area, the core city can have one set of rules while the suburbs may have entirely different sets. It’s all up to the locals to work out the intricacies of recycling plastics.
Just looking at my local area, St. Paul will take plastics 1 (PET), 2 (HDPE), 4 (LDPE), 5 (PP) and 7 (Other), but not 3 (Vinyl) and 6 (PS). They also don’t take plastic bags, but note on their website that you can take them to local grocery stores for recycling. Right next door in Minneapolis all plastics except expanded polystyrene are accepted. And no bags either, but the site makes no mention of the recycling options that St. Paul's site did. In expanding the circle a little, St. Cloud, Minnesota takes only 1 through 6, and Brainerd, Minnesota doesn’t have a recycling program at all [*].
It's local market conditions that cause these variations from place to place. If there is demand for the recycled resins, the materials will be accepted.
[*] Maybe because they once got body parts in their chipped wood at the composite site.