to the best of my knowledge, in nj, you do. police are not allowed to run a tag, until they've stopped a vehicle. of course, this doesn't mean that they don't.
Cap, even though NJ is a planet all on its own...

All kidding aside, the person that has a vehicle registered in their name
owns the vehicle. They
do not own the registration plates, the RMV does. Police don't need any probable cause to check a vehicle's registration nor is there any expectation to privacy. Therefore there is no 4th Amendment violation. If a police officer stops a vehicle for a legitimate purpose, they cannot search the vehicle unless the owner/operator gives them permission or if the person is arrested or probable cause exists to search (i.e. the odor of narcotics). The vehicle is searched as part of the motor vehicle inventory laws. This prevents the arrested person from saying that there was anything taken from the vehicle prior to it being towed.
alarms go off for tags associated with a suspended license. sooo....suppose my girlfriend is suspended, and i'm driving her car? i have to put up with the cops bs because of this?
Good question. The answer is yes and no. If the vehicle is registered to a female and the police cannot identify the operator as being a male or female, then they can make the stop. If the operator is clearly not the registered owner (in the scenario you described, a female with a suspended license), and the police officer can
clearly, see the operator, then no. There is no probable cause to support the operator, being a male, is suspended.
And is it really "bs" as you descibed it? They are just doing a job.
Hope that explains your question.