From my experience dealing with the public over many years, we call the police as a last resort when someone is abusive and/or threatening to staff, when we cannot get them to leave or defuse the situation any other way.
Many times the day after someone is abusive or threatening, they complain to senior management that they are the one who has been abused. I think some of them actually believe they are the victims. Eyewitness documentation of the events usually ends this type of complaint quickly.
I doubt that scenario unfolded as "I refused to accept the car they wanted to rent me, so they called the police". In fact, this woman must have known that calling the police would bring her a lot of grief, scrutiny from her boss, etc, and I am sure if there were any other way of handling the situation, she would have done so.
Learn from your experience. Low paid people who work in customer service deserve to be treated with respect.