A book I read as a kid was set in a future where they were out of oil and couldn't make new plastic. Plastic became very expensive and things like plastic bowls were used as signs of wealth. The plot involved kids who were taken and forced to mine plastic from old landfills.

https://en.wikipedia.org/wiki/The_Ear,_the_Eye_and_the_Arm

> The plot involved kids who were taken and forced to mine plastic from old landfills.

So basically what 3rd World countries do with the U.S. electronics.

> where you put products that can't be reasonably recycled today in the hopes that in the future someone figures out a way to do it

We have those; they're called landfills.

> neatly separated pile[s]

The problem is that most types of refuse are already semi-uniformly mixed at the household level, so you would have spend labor separating them, which might not be needed[0], so you might as well put off separation until know you need it.

0: Eg, if the most efficient way of recycling them turns out to be: dump the whole mess into vat of genetically engineered bacteria, and sift out the glass and metal bits when they build up.

"Genetically engineered bacteria" is basically pixie dust at this point. It's a potential solution, but we don't have the tech to know if it would even be practical.

Er, yes, that's exactly my point.