Constraints on individual liberty as it harms or restricts the liberty of others makes sense. It becomes nannying is when it restricts your liberty for your own good. it should be illegal to drive while drunk because you will crash into someone else and hurt them, but seatbelt laws are nannying because the only person you're going to hurt is yourself. And to get out ahead of it, if your response to this is some tortured logic about how without a seatbelt you might fly out of the car or some shit like that you're missing the point entirely.
