Maybe I'm too old school, or just big on sanitation requirements governed by the state and the Board of Cosmetology, whatever my issues regarding this subject can be; I know for sure a shampoo service shouldn't be addidtional it should be a given.
It's crazy to think that a customer or client should have to pay extra for a shampoo or have their hair already shampooed and blow dried before they come to a salon. I can't speak for the kitchen beauticians or the ones doing cosmetology services without being licensed, that is another story, but licensed cosmetologist in a salon should know and do better. Of course a salon service requires time and skill but hey isn't that the reason we became hairstylist? There's a certain type of feeling knowing that you are changing someone's life or making them feel better with the passion and gifts you have with just your two hands. I personally believe a shampoo and conditioning treatment is the beginning of a crafted hairdo but also a confirmation that your hands are working in a clean head of hair.
Shampoos help remove dirt, debris, odors, sweat and oil. The hair gets oil from the sebaceous glands, which keeps the hair moisturized. Moisturized hair is less likely to break or look dry and fuzzy. But too mush moisture can make the hair look greasy, limp and dirty. Most shampoos are designed to strip excess oil, which helps the hair become cleaner and more accessible to conditioning treatments, heat and styling products. A lot of customers have dandruff or more specific scalp conditions like psoriasis. Regular shampoos and treatments can help with those scalp conditions.
I can go on and on about the types of hair and services that should include a shampoo, no exceptions. But for now I will just say a shampoo before a hair service should not cost more or be a requirement for the customer to do themselves. Licensed professionals know that healthy hair will always ensure repeat business. If a stylist is telling you to make sure your hair is shampooed before a service, ask them to see their license. Real cosmetologist know that a requirement in hair school was to complete so many hair shampoos before you can go to the next level. So shampooing a customer is second nature to a salon professional.