Why do hairdressers always ask what shampoo I use, are the expensive shampoos / cond better ?

[scatteredglitter]

Every time, every time I get my hair done almost at the end hairdresser asks me 'what shampoo are you using' and starts a hard sell for the stuff they stock
If I say I use supermarket / boots shampoos there s usually a silence, eye roll, implied disapproval and i m told if I buy the hairdresser one for 4 times the price it will improve my hair condition and make the colour last etx.

So is this true ? Do pricier shampoos and conditioners do a better job ? I mean I have tried them but I m not convinced, but maybe I m missing something. Any hairdressers out there able to explain what the difference is

Supermarket stuff for me but change it around as that seems to make a difference.
However. My daughter swears by a range sold for afro hair in supermarkets and I’ve been using that and it’s lovely. My hair is so shiny and soft and smells great. (Am white with coloured dry straight hair).
I am not working for the company as I can’t remember the name but it’s short bottles with square sides and gold caps. Tesco stock it.