Some parents just feel bad/uneasy about providers making food. I provide all food and beverages but one of my moms feels so bad about it and feels it is silly that I should provide milk/juices/choco milk etc and will send her child every day with two full sippy cups and says it is to 'make things a little easier' on me. I tried to protest the first day or two but gave up. I know she means well.
I have another daycare child who EATS A LOT. Seriously - A LOT. Her mom often asks if she should send food and says she feels bad because she knows her child has a big appetite and that she would be happy to send food or pay extra a day. I declined but it was nice of her and she brings it up every couple of months.
Personally....(when I was a daycare parent) I sent the food and snacks for my children and the drinks. I still paid the regular fees. However.....my children are on a no pork diet and my husband did not feel that we could rely on someone to check labels or meals carefully to avoid pork since it wasn't an allergy but a restriction that he wanted enforced. None of our daycare providers minded since we still paid the same.
Eventually my son was also diagnosed with soy and dairy allergies so it became even more complicated to expect a provider to serve food and check labels so we just were relieved to send everything that he needed. It was also GREAT because the provider sent back the containers as is and we could see how much each of our children ate or not. As a parent - I liked knowing how much he ate etc