I’m not sure your risk analysis is correct, if the driver is going to do those activities anyway, without the aid of self driving tech.

People already do things like grab food from the backseat, fiddle with the music, read their texts etc.. while driving. Are they less of a risk to those around them if they have some self driving guard rails? I would argue very likely yes.

Your conclusion of “you’re bad if you do this, so don’t do it” is rarely going to change human behavior. Giving people a tool to make the behavior they already want to do much safer is more likely to succeed.