It’s still the truth
Often the rule that the customer is always right means that Karens get away with doing whatever they want to do, once they have spoken to whoever is in charge. They can have a second refill on their coffee, even though the sign says only one. They can bring their 6-year-old on the bus for free, even though over 5s have to pay.
Occasionally, however, the Karen will meet a manager who sticks up for his staff and isn’t going to be beaten down by some broad in designer sunglasses. If you’ve ever seen this happen in real life then you’ll have felt a small thrill watching the manager come out and tell Karen exactly the same thing that the server just did.