There are some things it is legal to give away but illegal to sell. It is important that this distinction should exist. For example, donating body organs is legal, but selling them is illegal. Aonther, example is sex. Giving out sex is legal, but selling it iis illegal in some places. The reaeson for the distiction is for the society to avoid ceating market for these things. If there were a market it would incentivize people to do things the society do not want. One can give away their child, but not sell her/him. One can give away sex, but not sell it. One may want to give those away, but they just cannot make money doing it. That is why there should be a distinction between the things it is legal to give away but illegal to sell.