This might shock many of you, but there are lots of laws on the books that aren't enforced for a variety of reasons. Usually it comes down to resources vs the importance of enforcement.
You eve see articles every now and then about how somewhere it's illegal to wear boots on Sundays, or some such nonsense? There was probably some dumb reason for it at the time, but no one is enforcing it now because it isn't worth the resources. That might be a silly example, but the principle is the same--there is discretion about where to put resources for enforcing laws.
This is just one of those little facts of life that's always been true, but is now suddenly completely unacceptable for the purposes of calling Obama a dictator.