I am a periodic shopper at COSTCO and always appreciate the chance to return home with my trophies of months-long supplies of various things.
What I just focused on is that COSTCO is way ahead of its time in terms of the waste it produces or does not produce. They have no plastic bags to give out and therefore none get thrown away by cutomers. You can buy reusable plastic bags, which I have done, that include one insulated model, there for COSTCO and other shopping uses. In addition, for those who want to put their purchases in containers, COSTCO always has a bin or two of discarded cardboard boxes available at no charge. Whenever I use that option, I am always certain to send it off to cardboard recycling after I get back to Chapel Hill (from Durham, the closest COSTCO store).
Finally, I notice that I rarely have any waste from packaging I acquire from COSTCO products that I cannot recycle. Virtually none of it goes into the "all other" garbage.