There are deep psychological reasons and explanations for this:
When you do the best for your client, you thereby activate the positive, plus form in him, he has a good mood,
the person experiences well-being.
If a person does not receive anything or the services received do not meet his expectations — he falls into his negative, minus form. From this negative, not prosperous form, he will be dissatisfied and in a bad mood.
You do a plus, the best — you activate plus forms in a person.
If you do a minus, if you don’t give the best — you activate negative, destructive forms.
If you look further, it works as follows:
If a person is in a destructive form, he can only destroy from it. And he destroys (of course, unconsciously) everything that is in his world: physical and emotional space. In such states, a person is tense, he is not friendly and not generous. We can say that at a certain level, a person is under stress.
If a person is in his positive form, then he is creative, he feels a plus, he has everything and he vibrates into the world with a well-being. On the manifested level: a person is generous, “sings and dances”, spends money, buys impressions.
Therefore, the peoples who understand and feel this principle are usually very hospitable.
To give the best means to lead a person into his best mood and best states.
Therefore: give the best to your guests and customers, do more than they expect. And everyone will be good from this.