Here is just one of pages an pages of stuff from the Facebook group. Mainly US but situations I have witnessed over here.

(American Contributor)
I have four pet hates.

1. "I want an SM58". No, trust me, my AKGs are loads better for most singers. I even carry a fake SM58 that sounds like shit so I can put it up to prove my point to the expert vocalist. When it's the drummer wants an SM58 in his kick drum rather than my Beta52 I get quite cross.
2. "I want kick drum in the monitors". No you don't. You are standing right by the drumkit. Moreover, most monitors don't have the LF to reproduce kick drum anyway, all you are going to do is add distortion and probably rip the little 10" speaker (even if it is a 500 watt one) off its suspension.
3. "Can the monitors go any louder?" Sister, you have got over 2 kilowatts in the monitors. That's more than Hawkwind used to use in the 70s. You could of course persuade the guitarists to sober up and use a setting other than 11 or put some mid back in their amps or if all else fails use a powerbrake.

Then of course the guitarist who noodles at 11 while you a re trying to coax the singer to open their gob during soundcheck so you can get ANY idea what settings the singer needs. I used to carry a 2 inch baulk of timber labelled "Nathan" for such occasions. I once worked with a guitarist called "Nathan".

I'm definitely going to order some T shirts for this year that'll say.
"We're Not Happy, til You're Not Happy."