I don't think it should every be required by a business otherwise it should already be in the price per person. So it really should only be recommended.
I think anyone in this business depends on tips. Although I think if someone owns that actually company then it is kinda weird to tip, because they are already setting the price.
I tip on the service and what I feel is right not what someone suggests.
My friend is in catering sales at a large catering hall. She does not work on commission and her salary is terrible. I know she gets disappointed sometimes because she says that she will do SO much for a bride & groom and she barely gets tipped.
I am having a destination wedding and plan on tipping all the people that help me along the way that I feel are truly helping me out. I just tipped the person doing my invites SO was SO helpful and really took her time with me. So I gave her $20.00 She was SO appreciative.