Have you ever looked at media law or libel law? It does not have clear boundaries, but journalists are still expected to follow the law. Journalists are not absolved of the responsibility because it’s complicated.
You just need to not break the law. It’s how it works. If you don’t want exposure to liability, you need to acquaint yourself with relevant law.
They absolutely have boundaries that a lawyer or prosecutor can use to make a case in a court of law. How do you think the law works? Interpretation of laws is a big part of how the common law system works.
You can't prosecute someone for murder just for insulting you. You can't prosecute someone for robbery if all they did was jaywalking. Media laws have clear boundaries sufficient for legal professionals to do their job. Building codes have clear boundaries sufficient for legal professionals to do their job.