It seems obvious that the legislators intended this to apply to new uses, not existing uses. How do they pass a law that doesn't actually mean this? Were the

It seems obvious that the legislators intended this to apply to new uses, not existing uses. How do they pass a law that doesn't actually mean this? Were the drafters incompetent? Is it some kind of con where they deliberately pass a law that appears to say one thing but actually says something else? Honestly, as a non-American this seems bizarre.