Well, when backing out of a driveway in R, you have to stop the vehicle. Put it in D. Give it a second to change gears to D, then gently apply the throttle. If you slop it from R to D and floor it simultaneously, the gearbox will slip, shudder, and fail to respond because it simply cannot do what you ask it to do, which is do 3 things at once. A had a friend who was a terrible driver and never stopped when changing gears on his Toyota. He ended up stalling the vehicle on multiple occasions.
Folks, you gotta realise that the AT is an extremely complicated mechanism.