Those of us who toil year after year performing services for others like to know that we are appreciated. If it's time to go home and a customer wants something done, am I going to stay late for someone rude and pushy? Perhaps not. If a regular customer who spends money and treats me like a human being wants something, I'll likely oblige.
In my work there is a lot of pressure at times and I may be given 20 cars in one day to sort through. If I can't get them all done, I have to decide which ones get priority. If someone is a pain, they might have to wait.