I have a (possibly half baked) theory that the solution to a lot of waste is to put pressure on the suppliers through the retailers because unfortunately much of our world is driven by cost, and sometimes the worst environmental options in packaging are the cheapest.
My example store could be anything from Costco to Ikea to Aldi to Walmart or whatever other bit of everything store you have in your bit of the world. I want to put the onus on them to push for better packaging options by making it compulsory that they as the retailer accept packaging back at the store, comingled (unsorted).
So I go home from the shop with my new gadget, it comes in a cardboard box, wrapped in a plastic bag, with polystyrene brick padding. The shop also sells food and I buy some stuff that's tinned as well as a chocolate bar and a drink in a bottle.
Next time I go back to the store on my way in I can just drop off the box with all of the packaging from all the items in it. They have to take it and they have to recycle it.
Suddenly large multinational retailers are putting pressure onto their suppliers to (for example) stop using polystyrene, its tricky to mechanically sort from other stuff and find a recycling stream for, use cardboard padding instead. Use a paper bag to wrap the item (if neccessary at all) in stead of a plastic bag as it can go into the same waste stream as the cardboard.
Mechanized sorting of (some) comingled recyclables is already possible, but there's no incentive to package goods in these easily sorted/recyclable materials.
Manufacturers will get on board pretty quick if large retailers say "we're dropping your products unless you change how you pack them" and they'll be saying that pretty quick once they're responsible for the packaging recycling.