That is not what being a professional cook is about though. My girlfriend is a pastry chef and it takes more than being able to follow a recipe. Part of being a professional means knowing why certain ingredients taste the way they do when mixed with other ingredients. It means knowing how the altitude and temperature of where you are cooking can affect the taste of an ingredient. And there are a lot more little details that go into it as well.

For most people, they are just going to follow a recipe and you are right, that is all they need. But to be on a professional level and to be able to reproduce those flavors it takes a lot more than that. Check out the book "Professional Baking", it shows a lot of the complex nature that goes into being a pro.