Lunch at home?

According to my unofficial WPS historian, sending kids home for lunch stopped in 1965-66.
If you even vaguely have a sense of the dates many of our elementary schools were built, this makes lots of things make lots of sense.Why, for example, are so many of our Baby Boomer era schools lacking kitchens? The kids were still going home for lunch (and those rooms they eat in? Intended as gym/auditoriums).
Thanks, Jack!