I live in the bay area and have worked for several of the big tech companies and startups. The only time I can remember anyone discussing mission statements was

I live in the bay area and have worked for several of the big tech companies and startups. The only time I can remember anyone discussing mission statements was when I interviewed at AirBnB. They had a full interview (30 mins IIRC) just about the company mission. The explained that it was very important to the CEO. I apparently failed that interview and they made me do another with a different person about the same topic. It was very awkward.