Hence, the staff in those schools was extremely strict, especially the lunch lady, so that the students learn to adjust to the harder way of life. She used to make the same porridge everyday, and gave only fixed amounts of food to everyone, to keep the children away from any kind of luxury.
Although the image of that lunch lady is still in the minds of children today, not one school has a lunch lady of that caliber. Today, children are not scared into doing something, but are politely made to understand between right and wrong, and their consequences. For instance, if children need to be stopped from eating a lot of candies, they cannot be forced or scared into doing it, but be explained the harmful effects of doing what they are doing.
I believe that this image of the lunch lady should have been gone with the extinction of old boarding schools, but media was always there to save it from dying, and has still kept it alive. Fairy tales and other children's books have played a major role in keeping the lunch lady alive. The stereotype can be seen in stories like Hansel & Gretel, Cinderella, Sleeping Beauty, and others.