Level 3 is not useful. Humans can't do the rapid task switch that's imagined, so in practice you're still supervising the car at all times even though notionall

Level 3 is not useful. Humans can't do the rapid task switch that's imagined, so in practice you're still supervising the car at all times even though notionally SAE says that's not what you're doing. Or, likely, you aren't supervising (e.g. you're looking at your phone) and so each such transition is incredibly dangerous.