It's rude not to pay people for their services.
Todd noticed that his car has been making a weird squeaking noise.
Todd wants to take his car to the mechanic.
Todd takes his car to the mechanic and pays him for the work but tells him he thinks the cost is high.
Todd has his car worked on by the mechanic but refuses to pay because he thinks the cost is too high.
The mechanic thanks Todd for his payment and apologizes if the cost seems expensive.
The mechanic gets annoyed and tells Todd that he has to pay because he has already done the work.