If you put a murderer in prison- the victims families will help pay for their food with their taxes. That is unjust on its face
This is incorrect. The negatively affected parties are paid compensation. If the murderer isn't able to pay, society pays. Its worth it. I an as anarcho capitalist as anyone, but that doesn't mean we stop having a court system. You can find all sorts of ways of paying for it, it doesn't have to be taxes. But if any tax is justified, its the tax that pays for the judicial system.