I agree that parents should be teaching their kids to eat healthy!
Unfortunately, for various reasons many of those parents were never taught themselves what healthy things are to eat. Some, honest to God, do not know how to do anything cooking unless it's microwave food or noodles boiled on the stove. In many single parent homes there isn't "enough time" to cook at night because Mom or Dad are too tired. Easier to get Mickey D's or Pizza. 
This is where a supportive community can come in.
A group of parents can have a weekly crock pot dinner night. One parent makes a crock pot meal and the other bring bread, crackers, fruit, juice or help with paper plated.
Another community idea is for a group, Eagles, Elks, VFW, American Legion, to each take a turn in sponsoring a Saturday breakfast or a Friday night cook out.
Grandparents or single bored people that like cooking can offer free cooking classes for kids and their adult.
Kids do not have Home Economics any more as a required class.