As one of the largest retailers, you have the purchasing power to tell manufacturers to use paper, glass, or metal packaging only. Start a foundation, invite every major retailer (especially your biggest competition) to join you and use your combined purchase power to force the manufacturers to go back to the pre blister pack, plactic soda bottle days of ~50 years ago. Force innovation in packaging by saying no to plastic packaged products.
I just think Amazon has a really good position for that. What are viable policies and technologies it can use to solve the plastic problem?