alt Hacker Newsthings that directly harm other taxpayers - murder, physical violence, theft, false slander/reputational attacks...
prohibiting things that harm the individual should not be the role of government, IMO. Government, in the liberal/Enlightenment tradition, is there as a protector of your 'rights' to life, liberty, and property. While it has a duty to protect you from things which could harm you (eg junk food/sugary drinks), it also has a duty to let you do what you choose to do, even if it's 'bad' for you (eg eat junk food and drink sugary drinks).
Hence the compromise - you can smoke cigarettes and drink Coca-Cola, but the makers of cigarettes and soft drinks have to warn you beforehand, and the transaction may be more taxed than things like basic foods.
In countries with public health care and social security, harm to the individual is direct harm to other taxpayers. You must wear seat belts or wear bike helmets because the rest of us don't want to pay your rehabilitation bills.