breakfast fundamentalists

Why are some people so rigid about what is proper to eat at what meal? If a person is happier sticking to the food that is common their culture for a particular meal, fine. But, why should they make a big deal about what other people eat? Breakfast cereals didn't even exist all that long ago. When I eat at home, I eat the same things for breakfast that I eat at other meals, and guess what - nobody's ever arrested me for it! Just another example of how some people are really threatened by anything different, no matter how innocuous. But they are happy to benefit from the creations, such as air conditioning and cars, of those who did think differently from others.