The styrofoam like used as cushion is known as expanded polyethylene and it belongs to LDPE with sign 4.
The thing about the codes are enforcement level differs. The overseeing agencies focus on the big manufacturers thereby leaving small level players without proper monitoring.
This is why you see electronics having the recycling sign and code stamped on them but the packaging material have none.
With proper enforcement and enlightenment, individuals can understand the type of plastics and know if they are easily recyclable.