It won't work for the same reasons you can't just transplant a heart or other organ without taking powerful antirejection drugs for the rest of your life.
The grafts from hair tranplantation between indivduals would be recognized as foreign by the recipient and would be rejected. You could take antirejection drugs to overcome immune system rejection, but the drugs are expensive, powerful and entail serious risks and side effects because they supress the immune system in order to prevent rejection. No physician would put you on these drugs to restore your hair.