Because of the number of interfaces in the environment, there are a near infinite number of edge cases. The mail point is that because we evolved a theory of mind with humans, we can more reliably narrow that number of edge cases with human drivers without having to experience it first. Having an AV learn those edge cases bears some risk, and that risk may be carried by unwilling members of society.
Unwilling members of society are already carrying the risk of every nascent driver entering the road for the first time solo and every aging driver who hasn't yet had the accident that loses them their license.
That's the point of the risk part of the comment. Because we've evolved to have a theory-of-mind with other humans, we can at least know or intuit some of that risk. That's different than accepting a black-box risk. The whole point of the trust part of the comment is that, in order to build trust, we need to have risk-informed decisions.
