Well The United Nations has already given us an answer for this. Greenies need to start eating insects grown locally (or at home) and then there is no need for buying groceries and carrying them in a bag. Besides these bacteria have rights too so greenies may want to just accept using the bags anyway.
Then there also should be respect for their stomach and intestinal bacteria which these Greenies are killing by the millions. Heaven help them!
Maybe the Greenies should just stop eating altogether?