Why is the price of herbal tea shop so uniform?

Compared with the money that can be sold, there is too little money for Chinese herbal medicines in herbal tea. For example, a Siraitia grosvenorii can make 50 cups of herbal tea, each cup of 2 yuan. What do you say is the profit? Of course, this is a metaphor, but the profit of herbal tea is really great. Many Chinese herbal medicines are very cheap. Some black-hearted bosses add western medicine for curative effect, which is cheaper. As a boss, the cost of each cup of herbal tea is less than 1-2 cents, and it costs 3 yuan. What's the difference? For the convenience of management, it is normal to unify the price.