The picture will show the license plate and the driver so I would have to assume that it would also show the vehicle number in the case of a package car.
Everything you say is true. I would need the exact reading of the law to know how a particular state does it. I know a little more about New York than other states and since you live there, let's work with that state.
New York State treats the red light offense as a parking ticket. Pictures of the driver aren't necessary nor are the cameras set up to get the picture of the driver. The camera is set behind the intersection . It is not important who the driver is. The ticket is sent to the owner of the vehicle, just as if it were a parking ticket.
In the case of a UPS package car, if the plate number does not show up clearly in the picture, then what is the person (who is trying to decipher the picture) to do? He knows it is a ups vehicle, he can see the vehicle number but to whom does he send the ticket with the right information on it to ? He doesn't have a database to match ups vehicle numbers with license plate numbers. If you receive a parking ticket without the full license plate number on the ticket , it would be dismissed (no cop would write a non moving violation like a parking ticket without a license plate number). The same would happen with a red light camera ticket.
Maybe other states do it differently but in regards to this, I believe the procedure would be the same.
Maybe, you UPStateNYUPSER , are thinking like a cop when it comes to determining the identity of a wrongdoer. For example, let's say a package car driver did a hit and run and blew a red light after he hit another vehicle and set off the camera. Let's say the camera caught the back end of the ups pc but only got the first two digits of the plate and most of the vehicle number(one digit obscured). Then the cops would use the info they got to narrow down their search and I am sure the nearby hub would get a visit and the offender would get charged for hit and run eventually based on that spotty info.
But for all intents and purposes, this is just like a parking ticket in New York and without the full license plate number(that is the crucial evidence) , no ticket.