More questions about gratuities and tips!!

I read the posts below about this topic, but I need help w/ gratuties and tips for the staff at the hall, not outside vendors. I was told that I will have a Maitre D, Captain, and Bridal Attendant and that the customary tip for them in that order is $2-3 pp, $100, $100. First, do I even need 3 people? In your honest opinion, do these people not get paid well enough from the hall (like the wait staff)? I'm asking seriously, because I'm trying to figure out why they suggest to tip them this much. Is this a way for the reception hall to pay them less, and depend on their customers to make up for the salary? Of course if they do a fantastic job, they should be compensated, and I will do what we can.
But for example, does the MD work harder than anyone else, that he deserve an extra few hundred after 5 hours? I'm not trying to be sarchastic, I am really curious about this and want to know the reasoning. And, I'm a bit frustrated because I did not include these things in my budget. Thank you!!!