I can tell you that rude behavior in restaurants or cafes is not uncommon. It can range from being impolite to the staff, making unreasonable demands, being loud and disruptive, or even engaging in offensive or disrespectful behavior towards others.
In such situations, restaurant staff are usually trained to handle difficult customers professionally and calmly. They might attempt to address the customer's concerns or issues, or they might involve a manager to mediate the situation.
As for diners who witness rude behavior, it's essential to avoid escalating the situation further. Interfering directly with the rude person may not be productive and could potentially make matters worse. Instead, it's best to let the staff handle the situation and, if necessary, provide them with support by remaining patient and understanding.
If you encounter rudeness while dining out, it's crucial to treat the staff and other patrons with respect and understanding, and remember that everyone is entitled to a pleasant and enjoyable dining experience. If you have concerns about the behavior of another diner or the service you are receiving, calmly communicating your concerns to the staff is a more constructive way to address the issue.