Don’t serve her. Close the drive through.Call the police. Send an employee out to take the orders of those in line. Tell them to park, as McDonalds does when your order will take longer. Take the food out to those people as their orders are completed. Tell them there is an ongoing problem and ask them to please take their order away with them so that there will be parking available, if that is a problem.
To all appearances even THAT didn’t happen, doubtless due to some corporate rule about not going out when a difficult customer shows up, because of the litigational dangers.
They know her license plate. It’s sitting right there in view of the order window. Just phone police and let them take care of the unruly customer afterwards, with disorderly conduct charges or whatever.
Your answer is of course the correct one. One other thing I would reccommend is to put a curb in there so no one can cut the line.
There will always be one who will try this. It wouldn’t make any sense to be one if you couldn’t act like one.