On a theme of Concerts and Performances:
Concerts/shows that people actually arrive to be seated before the performance starts, not "fashionably late".
Concerts where people actually SIT in their assigned seats, and don't stand and block those who wish to or need to sit, often for THE ENTIRE SHOW! (I mean, really people! OK, you are excited to see your favorite artist, especially at the beginning of the show... so stand up for the first song, then SIT YOUR ASS DOWN).
People being quiet and listening to a performance, not talking to their companions as if they are in their own living rooms. In other words, thoughtfulness of those around you and the artist who is performing. We really don't want to hear about all YOUR drama.
Concerts where people actually watch and listen to the show. Now days, I see many people who (often STANDING) are spending the ENTIRE SHOW holding up a cell phone and recording. It seems they are missing what a live concert is all about! I would like to know the number of times someone is re-watching the hour long or more performance they recorded, as they watched it through a small screen.
People flicking their zippo lighters and holding overhead to show appreciation for a song. Lighters are now replaced with glowing phone screens, some of which have an app that is..... a depiction of a zippo lighter!
Joints being smoked at indoor concerts and just "passed down the line" (very 70's, I know!)