I was an apprentice chef, and it is true what you're saying, but it's still hard physical work no matter where you are. Kind of slightly more physical in canteen style settings (or the ones i was in) because you're cooking/carrying far bigger quantities of food, and still have fairly tough time constraints.
I used to work in the latter as a temp kitchen-hand, and most of the chefs there specifically quoted sane hours and working environment in general as reasons for preferring that over a restaurant.
Buying is is easier as you typically know fairly precisely how many mouths you have to feed. If you do end up with too much of something, then there's a stew on the buffet the next day. Said mouths are also less particular. If you arrive at the end of service and the lasagna is a bit dry, you don't send it back, you eat it anyway or pick something else.