The basic idea is simple: Efficiency.
We should not have to have a fleet of vehicles that ONLY transport passengers or a fleet that ONLY transports people. This is just another reason for traffic, congestion, and pollution. There is no reason that we can not efficiently deliver people and packages around a city with all of today's data systems.
I would like to see vehicles capable of moving EVERYTHING around a city and see how much traffic & congestion is reduced by this.