One of the main selling points is that commuters can save time (the focus on self driving cars, not trucks/rail). However, long commutes are mostly a constraint imposed by suburban sprawl and associated planning failures. The same applies to automated delivery mechanisms from shops, again of limited use in sufficiently dense communities. In such a scenario, this feels a lot like optimizing 1% of execution time in a program.
For large scale transport of goods or people, the same situation applies for the economics - the labor of the driver should be a small fraction of the operating costs. There could be some safety benefits, but this remains uncertain. I found https://www.bloomberg.com/view/articles/2015-05-28/cars-will... quite interesting in this respect.
Seeing what happened with the invention of the automobile, I won't be surprised if self driving cars become the norm somehow. In the most extreme case there might be an outright ban on non autonomous cars at some point in the future. This is something I certainly don't look forward to.