this is an amazing discussion.
over the years in the corporate rat race, not sure I can accurately count the number of events where it was "okay, Dilbert, you handle the caterer." probably something on the order of 60-70 events; small stuff (10) to large stuff (3,000) now, true, it was the company's dime, but there was always a budget - and I was held accountable for budgets, just not with my own checking account. hmmm, perhaps indirectly . . .
from my perspective, the waitstaff and the musicians are working. they are not there to be feted, fed and entertained. otoh, the officiate at a wedding is part of the wedding party - anyone need to count brides and grooms? anyone line item billing the bridesmaid count?
background: I reiterate the statement previously provided: "Never run out of food."
booze I suppose could be more of a disaster.
so there's a five person band at a one hundred guest gathering.
see: food and the running out thereof. double check: percentages
the next issue is: is this a two hour thing, or a wedding reception from 2 PM until the last guest drops under the bar?
short affairs I would expect all the staff to come and go without the need for an interim food stuffing.
the left overs are up for grabs to anyone with a hankering.
for long(er) affairs I always expected the band, the juggler, the clown, the waitstaff, the bartender, etc., should be provided for. exception: no booze provided to non-guests.
I never ever recall seeing a specific charge to feed/water "non-guest" personnel. I suppose the caterer worked it into the overall cost. heh, works for me. if the chef is putting stuff on a platter whilst a tray passer is taking stuff off the platter in the kitchen, hmmm, that's what them big knives are for.
I had only one rule, laid down in stone after my second experience and put on my catering checklist: I never want to see the waitstaff hanging around eating with the guests, or in sight of same. they are working - what happens in the kitchen / out of guest sight is fine with me - enjoy.
it may be hard for you pros to believe, but I once intercepted a tray passer munching off the tray as it was coming out of the kitchen. no, I was not a happy camper and yes I corrected that situation on-the-spot and yes I expressed my displeasure to the caterer, also on-the-spot.
I had the same issue with an employee who showed up at work (almost) everyday with breakfast at the desk. the first 30 minutes of the employee's day was devoted to breakfast. it did not last.