That is a good point but my question was what if everything was free and therefore if it was free,.. we wouldn't even need to trade anything for anything.
When the robots take over production they may give things to people for free.
When people make things with their hands, they usually need something in return so that their family can survive. For example, you might raise chickens, and your neighbor might raise cows. You give your neighbor some eggs in return for some milk, and you both have a good breakfast.
If your neighbor gives away all of his milk for free, what will his family eat?