Detrus is talking about proper food.
You're talking about butter and mayo.
A huge part of the problem is that people equate these things just as you have. Mayo in particular is an abomination. What we have come to accept as "food" is tragic[1].
Hey! There's only 57 calories in a tablespoon of mayo. If people are responsible and only use one or two tablespoons (to dip their fries, for example) then it is totally fine!
People need to learn to eat slower and really savour the food. Small portions of more intensely flavoured food is way better than huge, bulky meals of starch and meat and sugar. Whole grains too! I used to eat a half pound of regular pasta topped with several cups of cheap meat sauce. Now I eat 1/5 of a pound of whole grain multigrain pasta mixed with 3/4 cup of high quality marinara sauce (no meat) alongside a nice big salad (with minimal dressing). It tastes way better and is much healthier.
A huge part of the problem is that people equate these things just as you have. Mayo in particular is an abomination. What we have come to accept as "food" is tragic[1].
[1]http://www.livestrong.com/slideshow/1007800-11-banned-food-i...