How China ended the lie of recyclable plastic

Plastics are an incredibly depressing topic. I have questions!

  • I have heard that the price of virgin plastic is so cheap because important inputs are produced as byproducts of other petroleum processing. If those byproducts weren't being made into plastic, would it be easier or harder to handle their environmental impact?
  • Plastic has a lot of properties that are desirable for packaging. I'm sure there are many of those properties that can be reproduced by analogues if those analogues are produced at scale and thus cost-efficient. What do materials scientists think would be harder to get right?
  • Do governments fund materials research into plastic replacement?
  • Where do economists think it would be most effective to tax plastics to reduce their use / environmental impact? (I.e. at which stage of the production pipeline?)