The way this sting is described, the theft of these items would not be a vehicle burglary. A vehicle burglary occurs when the vehicle is locked with the windows rolled up and force is used to enter and steal the items. I suspect that the value of the items in this sting totaled over 400 dollars, which is the threshold dividing petty theft from grand theft in California. Had someone taken the items, the charge would have been grand theft, not vehicle burglary.
I work Auto Theft Investigations for a living in Texas, each state may vary, so I wont claim to know California law. In Texas, this would count as a Burglary of a Motor Vehicle. The vehicle does not have to be secured, if a thief steals an item from the vehicle, a BMV has occured.