The problem is that legally speaking these systems aren't treated as the primary driver, they're treated as an optional feature, basically just an enhanced form

The problem is that legally speaking these systems aren't treated as the primary driver, they're treated as an optional feature, basically just an enhanced form of cruise control, etc. Where they might get into legal trouble is if the driver was not properly informed of his duties. But I'm assuming it was pretty clear he wasn't supposed to be watching TV, he was supposed to be watching for the car to make a mistake and then correct it.