This happens all the time, and not just in Ca, and not just in the yards. They hop on and toss stuff off to a chase vehicle along the way. Or they hit the cars when they are parked along the remote sidings because they were staged for some reason. Breakdowns, repairs and such.
Cordless grinders with cut wheels allow easy removal of locks, and catalytic converters. Modern technology has made thieves work much easier, and quicker.