in the 20th century, when many people still worked in factories, after a long struggle, there were labor protection laws that protected the workers from losing their limbs, and even if they did, they got compensated for it.
In the service industry, the worker is expected to take whatever the customer throws at him. The customer can treat the worker like shit and get away with it. If the worker does something in return, he mght lose his job. This is completely unacceptable. Workers should have the right to refuse service to nasty customers. That will teach the customer to behave and will make the workplace a mentally safer environment. Service givers are not punching bags.