Indie car racing has a warmup before the pace car leaves the track and the green flag is waved. This allows the car and the tires to reach the proper temperature.
Since the OP mentioned a comedian, I’m reminded of some George Carlin bit where he comes on stage and then explains that he doesn’t want to just dive right in to the set, just like people typically dawdle for a time when they get to work (the part I recall best is when he notes that if you have a window to look out of, that accounts for a good 20 minutes).
As a lawyer who litigates, I actually don’t often go to trial. It does happen periodically, but the vast majority of time that I’m in court it’s for pretrial hearings and pleas. However, when I do have a trial, I like to come to the courtroom ahead of time and just “walk the room” - imagine addressing the jury box full of people, approach the witness stand, stand at the lectern, that sort of thing. If I have a client I expect to testify, I show them the witness box. I also show the client how the microphones at the tables work (you need to mute them if you are having a private conversation).
I guess you could call that a warmup. I have a trial at the end of this month, and as i was showing the client the courtroom I jokingly referred to it as like “batting practice before a baseball game”.
As demonstrated in this documentary:
AIUI, part of the “warming up” thing for an orchestra is that it mentally preps the audience, “The show is coming soon.” It does, for the audience, what playing movie previews before a movie does for a movie crowd. Those random chords or notes serve the audience notice, “Time to put the phones away.”
Some instruments at least change their tuning on account of the audience. But maybe not modern orchestra instruments. A friend of mine once gave a concert with a keyboard instrument called a virginal and discovered it had to be retuned after the audience arrived.
I thought those could be only tuned once.
I always felt that the cacophony of the orchestra tuning up their playthings before the performance was part of the performance. It’s part of the art form, and part of the whole experience for the audience. Without it, it would feel like some part of the show is just missing.
Those Europeans who don’t get to hear the warm-ups just don’t understand that they’re missing something.