I don't understand how it can become law. Are there any other laws that tell you how to do something, as opposed to the end result? Here, the idea is that you shouldn't hit cyclists with your door, and the way to achieve that is to look, and the "Dutch reach" is a good way to do it. Why isn't the law just "if you hit a cyclist with your door because you didn't look, that's your fault" instead of specifying a particular way of looking (which may be a problem if you have mobility issues).

The only thing I think may come into law is that it has to be taught in driving schools.