Here's another good example: what is the correct way to order multiple adjectives in English? If you are a native speaker, you probably don't have any idea, you just know that you say "an old big brown cardboard fridge box", rather than "a cardboard brown fridge old big box". The order is very specific and any deviation is obviously incorrect. Try it for yourself!

But any ESL student can tell you the order is quantity, opinion, size, age, shape, color, origin, material, purpose. We'd had to reverse-engineer the rules, and then teach it to newcomers.