Airbnb doesn't sell you a room to stay, that is what the host does. Airbnb sells you trust which is achieved through a platform of social commenting where no-one is anonymous. Everyone is known, named and identified. Anonymity verses privacy is a massive debate of our time which online platforms are tackling in new ways. I DON't think we should launch a platform called 'Vunerable.com' to solve the problem set by this brief as only the aggrieved would sign up.
Rather I would prefer to see open-source the code used by Airbnb and Hailo that make staying with hosts or taking cabs safer so that every platform can include high-end systems that protect their users which are all of us.