In a libertarian utopia an employer would be free to implement their own version of the Northern Territory Intervention. As the only private sector employer in a remote Indigenous community, they might choose to pay their workers using a Basics Card that can only be used at a company store. Naturally the store would stock only healthy products like fresh fruit and vegetables. The employer might also regularly test workers for drugs and alcohol — not in order to prevent accidents at work — but in order to encourage workers to adopt a healthy lifestyle.
According to Friedrich Hayek’s definition, this would be coercion. In the Constitution of Liberty he defined coercion as “such control of the environment or circumstances of a person by another that, in order to avoid greater evil, he is forced to act not according to a coherent plan of his own but to serve the ends of another.”
Libertarians object to coercion by governments. They strenuously object to coercion when it’s directed against employers or corporations trying to sell things like cigarettes, alcohol and junk food. But they don’t object to coercion when it’s part of the labour contract.
So it turns out libertarians don’t have a principled objection to nannying. In some cases, they’re all for it.