Superficially ecologically correct; whether it remains so under examination varies.
I remember the Earth Club, when I was in college, protesting the availability of disposable cups to take coffee or other hot beverages out of the dining halls. They made enough of a fuss that the college provided everyone with reusable plastic mugs.
Unfortunately, the plastic in the mugs was substantially worse in landfills than the cardboard would have been; if the consumption had been one mug per student per year, it would have been a wash. But the mugs, which were “free,” were thrown out and lost with reckless abandon, and people kept on using the cardboard cups.
So this was a great “green” effort, and there was much back-patting about how the Earth Club had gotten the evil wasteful college to reform its ways.