C.A.
It sounds healthier than a lot of babies get. The day care provider is getting paid to do a job, and should follow the guidelines set by the parents. If that child is under weight or malnurished I am sure the pediatrician is aware of it. When looking at the nutritional value of veggies verses fruits you will find that many of them contain the same types of vitamins and minerals. By not using a lot of sugars, even the natural sugars in the fruits, they are allowing the body to develop insulin in much better fashion.
I find it offensive as a parent to have a day care provider openly questioning the decisions of a parenting style. If there is a concern she should address it with the parents. If she disagrees, she can tell them to find someone else. But to be honest the decision to add foods to a childs diet against that of the parent, goes against everything I feel is right in this situation.
I know a couple of little girls that are alergic to many foods. They eat not grains (cereal), no dairies, and few veggies and fruits. There diet is very limited. However, they are very healthy and are able to maintain their health even on the restrictive diet. Thin they may be, but their doctor agrees that they are amoung some of the healthiest kids he has seen.
Some times other people need to just step back and put aside their own personal feelings, while looking at something objectively. There is nothing about the diet you described that is lacking in nutritional value. They get milk, water, veggies, and cereal. The get crackers and cheese. They are getting their fats, there veggies, and their grains. They are getting a limited diet of sugars.