This has happened dozens of times to me. Most customers seem to feel that employees are always subservient and treat them as such. So when a black customer comes along, something clicks and the worker feels the need to like belittle the black customer first before they're put in a position of inferiority. Its innate racism that is just bred into people.
The employee probably won't get in trouble due to her probably being able to deny service to customers she suspects of fraud.
Also, Zendaya's skin tone probably played a role in the employees actions, but what can you do?
oh dear poor Zendaya. Don't be fooled by her laughing and making joke about the situation. It bothered her! I hope Zendaya went back into the store and asked for the manager!
Just because it has never happened to you doesn't mean it's not real. It's very much real, even for powerful people of color like Oprah who was denied service/a product because they thought she couldn't afford it