I agree that med school is a field where much younger grads may face more difficulty with admissions than they might in a subject like physics. Everyone's options are different. It may be that for some kids who are finished with college by 16 and 17 they have more options than they did at 11 or 12. Older teens may be more able to travel, work, enter a master's program before med school, etc. Options that will be engaging but weren't a good fit for a preteen or younger teen.