[mrpopo]

Context matters in roadkill statistics. If a human driver risks causing more accidents on the highway when distracted and tired, a driving assistant risks causing more accidents in the city streets where there are more opportunities for failure.

Also, roadkill becomes a legal case. You need someone to be legally responsible. Driving assistants blur these lines.

It's not just a "killing fewer people per mile" problem (which would also have a huge causation/correlation issue).