Why do restaurants serve such basic means to their employees?

So I was at a really posh and expensive restaurant a few months back for lunch and while returning, coz the elevator was taking time I took the stairs instead. I noticed that dozens of their employees were sitting on the stairs and eating dal & rice hurriedly. Now I understand that dal and rice is a staple in our country but surely the employees can be given better food. I remember watching an episode of the Bear and noticed that a different chef would have the responsibility daily of cooking meals for the employees and they can cook whatever they want. Now this is a restaurant that probably makes lakhs every day. Imagine someone who works there serving the best pan Asian food to customers all day long and in exchange you get dal and rice. Now I am not sure that this is the case across all restaurants but I was quite disappointed tbh.