On Saturday, June 12, 2021 at 11:13:11 AM UTC-5, Commander Kinsey wrote:
Why do people say left hand down instead of left? We all know which way to turn the wheel to make the car go left, and it's the same in reverse. And if I'm reversing looking over my shoulder, one hand isn't on the wheel so the phrase makes no sens

The only thing I can think of is from the old days. There was a time when drivers used hand signals to signal
left, right, or stop with their left hands. That might still be legal but I don't remember anyone using them.