How often do live sound engineers encounter musicians or vocalists asking to be made "louder," even when the front of house is already balanced and the monitors were checked together with them?
In my practice this happens at every event. I'm certain it happens in my absence too - because even on a digital mixer with no physical interface, one that I worked on a year earlier, I come back to find it as if the remote control had landed in the hands of a child or a maximalist (they're psychologically close). Everything that could be turned has been turned: faders at maximum, gains clipping, routing duplicated, reverb tails set to infinity.
It probably doesn't need explaining that this is unacceptable. The first thing you want to do on setup is reset everything to defaults - but unfortunately that's not always possible.
What to do in this situation? One idea that comes to mind is custom software that allows a proper reset (where the standard tools don't allow it) and restricts changes to a short, acceptable range. I'll probably get around to building something like that soon.