I’m very confident that if you could sell your blood on the free market and avoid donation scamming centers, which literally are taking your blood for free (time compensation) and sell it, partly to the Pharma industry for profit, the problem of not enough blood would be solved quickly.
But blood counts as organs and organ trade is prohibited.
Actually, selling blood is legal in the US under the same law that legalises selling plasma. But hospitals won't use sold blood to inject into patients because even if it goes through testing for diseases, they consider it too high a risk.
But blood counts as organs and organ trade is prohibited.