A (deceased) friend of mine had an even better idea: resource extraction tax. Never mind VAT but instead tax for the use of virgin resources and leave the rest untaxed. The recyclers would put the miners out of business.
I fear this could also have plenty of unintended consequences. Depending on the tax, maybe more things will start being shipped in Teflon coated cardboard.
None of that stuff really matters directly though. What matters is actual impact on the environment. Things like pollution, habitat destruction, etc. That's what should be taxed/discouraged.
If someone can extract resources with no environmental cost, I would definitely NOT want to penalize them.
Tax the amount of plastic used in any transaction.
It would be amazing how much less plastic would be delivered if it cost something.
Plastic accounting - force companies to report on the plastic they buy or sell.