There is a scale for autonomous cars for the level of assistance the vehicle provides the driver. Purely mechanical systems at level 0 and fully autonomous, unsupervised operation at level 5.
The most dangerous levels are not unassisted or unsupervised, they're level 3 & 4 which offer enough assistance that humans struggle to maintain attention, and they're not locked in when the need arises.
There might be need for an autonomous coding scale.