"Sibia caught a glimpse of a revolver in the man’s waist, and let go. The assailant slipped out just as the train doors closed behind him, he said." I was under the impression that concealed carry permits are extremely difficult to get in the vast majority of California?
Depends on the County. I think in the majority of counties it is relatively easy, but in the counties that people mostly live, not so much. San Francisco and LA County in particular make it nearly impossible.
It helps if you know the sheriff or can be vouched for by someone the sheriff is familiar with. I imagine that in rural counties many middle-aged adults are only 1 or 2 degrees separated from the sheriff, anyhow, which suggests that rural and urban sheriffs are more alike then you'd think, especially if you exclude the two extremes; but the vast majority of people in urban areas will be too far removed from the sheriff's social circle. California's county-devolved permitting policies probably aren't quite as unequal and arbitrary as they superficially seem.