Strictly speaking, the money was detained. She stuck around to get it back/resolve the situation
According to her complaint, she was moved *by the manager* out from the check-out lane, to the front of the store and was accompanied at all times by the manager or some female employee until the police arrived. That’s a bit different than her just “hanging around, waiting to get her money back.”
I would also NB that this happened from a bit after 0100 to 0400 in the AM in the store. This is, in my extensive experience at Walmarts across the nation, when the store is being run by people Walmart doesn’t want to let the public see by daylight ... for very good reasons.
She has cause for a legal complaint.