On the Food network they boil potatoes, but they poach carrots. They poach turkey, but they boil eggs. They sauté’ onions, but they fry eggs in the same pan. Likewise, they fry hash browns, but they sauté’ onions in the same pan before adding the potatoes.
I can go on for days.
Grilled cheese is cooked on a flat top grill/griddle, most people use a pan in home cooking because they don’t have a flat top or it’s just easier for a single grilled cheese to use a pan. Reubens and paninnis are other sandwiches that are grilled. You could probably argue that grilled generally means cooked at high heat. Then there’s pancakes which are more commonly cooked on a griddle than a pan…