Vanessa did nothing wrong. It’s not up to her to make soothing noises to calm someone down who’s insulting and physically intimidating her.
I bet Vanessa isn’t the only customer who’s not impressed about the card-only payment thing. Not very “inclusive” of Starbucks but it was a minor grumble.
This tall, aggressive person reacted completely out of proportion, intimidating a middle-aged woman for no good reason. That’s not customer care or conflict management. Vanessa was not aggressive back, she was assertive - and good for her. Many people would have crumbled, too embarrassed and frightened to defend themselves.
I think the manager had a chip on their shoulder and was spoiling for a scrap with a perceived t3rf so they could brag about it on social media afterwards.