When you really look at it, only type 1 & 2 plastics are recycled with any real frequency (80+%). And even then, there is a subset of plastics marked with those two types which cannot be easily recycled.

Meanwhile, while types 3 through 7 are “recyclable”, in reality these are actually recycled in the very low single-digit percentages. Most of the rest are incinerated or shipped off to third-world countries for “processing”.

As such, most any plastic that are not marked type 1 or 2 should be binned with the trash, especially if said trash is going to be effectively and correctly entombed in a landfill.

Not only does it contain said plastics so they don’t contaminate the wider environment (especially if the landfill is correctly designed with a liner), but it also puts them all in one spot for when technology unlocks effective ways of recycling these types - there are emerging companies that foresee a time when we will “mine” our landfills for resources, and our best current strategy is to contain and concentrate our waste in as convenient a manner as possible.