Because it’s fun to teach children “old tricks” in a newer and needlessly more complicated world.
Because they’re being bullied and harassed into “being more environmentally responsible”..even though these plastic knobs keep being manufactured and keep riding on the sides of millions of drink cartons.
For whatever reason one wishes to entertain, since the words “open here” have been removed..show them the simple and intended way to open their cartons.
Heck, they may be able to remind their “betters” of this simple and safe alternative..if/when the lectures and environmental bullying start up again.