>>512602324It's not that one cannot eat food with one's hands. There are plenty of dishes that are supposed to be eaten with hands, like sandwiches or pizza. But all of these foods tend to have the property that nothing your hand touches should fall apart, or stick to your hands. Otherwise, you have a lot more to wash when you finish your meal.
>>512602388Gee, it's not like there's some property rice and saucy foods might have that all of the items you just listed don't have. You know what's nice about a hot dog? The bun is shaped in such a way that any toppings on top of the meat can be caught in the bread cavity beneath it. Assuming it's not overloaded with toppings, that is. It is food DESIGNED for eating with your hands.
Now look at a dish with rice and a curry sauce. Compare to a western dish like... mashed potatoes and gravy. Would you want to eat that with your hands, or would you think that something a bit too messy? You'd want a fork or a spoon, right? Even without the sauce, the rice is glutinous and might stick to you. It's also granular and might fall apart, spill on the floor, etc... A tool is ideal here. Unless you were to wrap it up somehow, like the Japanese do with seaweed.