The beetle is the photo is indeed a California root borer, Prionus californicus. And to answer your question, Yes, they are common. I opened my front door last night and one was sitting on my porch. They are widely distributed in western North America from Mexico to Alaska. The majority of their three to five year life cycle is spent underground as larvae, feeding on the roots of deciduous trees and shrubs, as well as some conifers, blackberries, and agricultural crops such as hops and grape vines. Adults emerge from pupae in the soil from June to early August and do not feed. The beetles fly at night in search of mates and are often attracted by lights which is why I found one on my porch. 

Thank you for your question.