I wouldn't say they were being childishly subversive -- it is very unclear that paper bags are better than plastic bags for the environment.

"Manufacturing a paper bag takes about four times as much energy as it takes to produce a plastic bag"

"Studies have shown that, for a paper bag to neutralize its environmental impact compared to plastic, it would have to be used anywhere from three to 43 times."

https://education.nationalgeographic.org/resource/sustainabl...