It may seem strange to think of a nurse or driver being more useful when contributing 30 hours a week instead of 40, but that’s because we don’t appreciate the potential range of their decision making quality, error rate, and so on.
In the long run, too, any job we don’t want to see become higher paid and more effective, we will want to see be eliminated or automated. So the effective pay increase would not uniformly drag on GDP across many industries.