But that's often _the source_ you need to work around; there is no way in hell that they're going to get all the light/sound/video/graphics ... etc people in the same 2 square meter area to put on a show like the super bowl :).

For smaller events like a touring act or even a venue with a few hundred people capacity you still need a single master clock but this time it's not "wall time" and is "absolute" time. E.g.: a musician at the front of the house chooses when to start and the video/lighting guy in the back needs to be on the same page so the visuals line up [0].

[0]: https://en.wikipedia.org/wiki/SMPTE_timecode