In my high school we had a salad bar, an italian bar, and the regular lunch line.
Was the salad bar in your school loaded with mayonnaise-based foods like tuna salad and potato salad, goldfish crackers, sunflower seeds and other high-calorie crunchy toppings, high-fat salad dressings, etc. like most salad bars are? A few tablespoons of regular salad dressing alone will do some serious calorie damage, i.e., “I’ll have some lettuce, carrots, cucumbers, and raw mushrooms topped with 1,000 calories worth of croutons and dressing.”
High school students might manage a salad bar neatly. However, elementary kids would turn it into disaster.