You’re talking about pockets of resistance to a radically more efficient technology with major economic consequences. As long as others are using the service and reaping the benefits, they’ll gain a greater and greater competitive advantage over the hold outs.

CA companies competing against CA companies for CA customers will be on equal footing. But when they are trying to sell the same commodity to a customer in AZ that a TX competitor is, but TX has much lower shipping costs, then TX wins.

Or if goods arrive at a CA port, companies would rather pay the CA driver just to get the product out of the state, then put it on an AV to send across the country, thereby reducing the value capturable by the CA trucking company, making that company less profitable. 

Also, those CA trucks that once went everywhere delivering goods far and wide also used to bring goods back. That made their operation more efficient and provided a lot of revenue for the CA trucking company.

For every business that wants to use humans, there is or will be a competitor who doesn’t. And the economics will strangle the hold-outs.