I read an interesting advice column recently where this guy wrote in saying how he was essentially perturbed (I don't remember the exact description) with hearing women use profanity. As he put it men used to use profanity when around other males and that was okay. The writer of the advice column rightfully so spun it right back about gender norms.
To an extent I agree with you but I think most of us see the elder generation be the ones scolding the most and yet also being one of the higher offenders. In general the people I see out and about talking on their cell phone at the table, listening to loud videos (or videos in general) without headphones on, having every tap of their screen make noise because they never shut off the sound to that, raise such heck over small details, tend to be the ones most likely to voice correction of others behaviors. Don't get me wrong younger people do some stuff too (especially allowing kids use devices without headphones) but if the social norms were completely different in the past I find the ones not adhering to it to be the very ones supposedly taught the "right" way.