It is none of the staff's business nor is it any of your business. Why does it matter to you whether the 10 people in front of you each took 1 of the item and there were 10 in the dish OR there is 1 person and he takes all 10?
The staff's business is to refill the empty dish and your business is to take what you want from that refilled dish.
If a dish is empty and staff are not moving to refill it, point that out to the staff.