Waymo gave me a ride in a car with no driver

I’m sitting in the back of a Waymo self-driving Chrysler Pacifica parked on the side of a road inside Castle, a former air force base in central California which was leased in 2012 by the company then known simply as Google.
On the beige headliner, behind the traditional driver’s seat, is a black rectangular panel and a series of four uniform buttons. My eye is drawn to the only bright blue button on the far right labeled “start ride.” I push it and a few seconds later th