I noticed a change in etiquette sometime in the 1970's. Swearing--particularly the use of the "f" word--became more common, even in public places.
I'm usually non-confrontational, but I have my moments. I hate it when there's a long checkout line, another cashier opens a new register, and the last people in line rush to be first. I've told people that there were others before them. Reactions varied.
At a large concert (Stones, Springsteen, can't remember), two large idiots were standing on their seats in front of my friend and me, blocking our view. I grabbed them both by the shoulders and pushed them down in their seats. I probably shouldn't have done that, but oh well.
There are so many jerks in society that it could be a full time job setting them straight.
A day or so ago, some jerk on the interstate in Milwaukee cut off another driver and gave him the finger. The other driver was Milwaukee County Sheriff David Clarke, who pulled over said jerk. It's nice when that happens. :)