“If the cop was REALLY “following the law” he should have arrested the McDonald’s manager.”
It was his duty to explain the law to the manager and that she had every legal right to stay and have the manager correct it.
If a business short changes you and you complain about it do they have a right to have you arrested for trespass because you did not just leave without wanting them to make right?
It seems many FR posters believe that management's complaint alone creates cause for citation and detainment.