Those constraints apply to humans too. So it seems likely that: - it's easier to get to human levels of safety on freeways then on streets - it's much harder

Those constraints apply to humans too. So it seems likely that: - it's easier to get to human levels of safety on freeways then on streets - it's much harder to get to an order of magnitude better than humans on freeways than it is on streets Freeways are significantly safer than streets when humans are driving, so "as good as humans" may be acceptable there.