Fraud is still illegal. What this means is that people don't have to prove the practices in question are fraudulent, just that the companies used them.
That's exactly why it would be more scalable as a court decision. A law can never encompass every possible dark pattern, while a new court decision can be added every time somebody discover something bad, and sue.
Additionally, court decisions will be more efficient, since once a pattern is found fraudulent, it is not only banned, but there is also a whole case of discussion to refer to. With a specific law like this, with no prior cases, we aren't really much further than we already were.
