It's a rhetorical question highlighting the contradiction of expecting unsophisticated systems that resort to follow-the-human tactics to be capable of self-driving inder more complex conditions in the last mile.
I have zero interest in debating the difficulty of freeway driving vs the last mile involves unmotorized participants and significantly more traffic control- that is settled in my mind.
So the hypothetical trucks can't handle freeways but can self-drive on much more complex urban and suburban roads?