It's a great quote, but a little misleading because it lacks context. Before you get on the train, you already know a whole load of background stuff about the train operator (rail safety stats, the fact there are legal requirements, health and safety laws and so on).

I don't believe we are conditioned to not trust people, but we are conditioned to be cautious. That means taking a few relatively safe calculated risks to build up a better picture, then trusting or not based on real evidence. When we take on a new administrator (DBA, sysadmin etc.), we don't promote their account to God rights the day they walk through the door; we sit down with them and steadily hand over important systems over time, evaluating how they act as we go. We're not distrustful of them, but similarly we're not treating trust as binary (I think I used that term in one of my posts last time this editorial was published).