The definition of a Level 3 car is that the driver doesn't have to watch the road ("the car performs the full OEDR") and that the car is driving autonomously without the need for a driver when in autonomous "Level 3" mode. There is no "take over immediately" in L3 so there is no need for hands on the wheel. You can watch a movie in an L3 car (but you need to stay in the driver's seat). In an L2 hands-off system you still need to watch the road at all times and are just getting help from the car to steer and adjust the speed.
In the Tesla owner's manual it clearly says that "
Full Self-Driving (Beta) is a hands-on feature. Keep your hands on the steering wheel at all times, be mindful of road conditions and surrounding traffic, and always be prepared to take immediate action."
Learn how to enable and use Full Self-Driving (Beta).
www.tesla.com
That's the description of a Level 2 driver assistance system.