Remember the last time you were at the grocery store and the clerk responded by saying something unrelated to what you asked? This cashier is focused on ringing up your items. They don't engage you at all. No hello; no how are you; no did you find everything. He or she finishes ringing up all of your items and you forward a have a nice day and they respond with something canned like you're welcome. You're welcome? Did I say thank you? No, I didn't. I offered a pleasantry. Just have a nice day. Goodbye, our business relationship has completed. Have a nice life. This is just simple and common courtesy. It is being polite. Your parents should have taught you these things as a child. If you want something, say please. If someone holds the door for you, you damn well better say thank you...and if someone thanks you, say you're welcome.
So, why do so many people forget this in business? I understand some customers can be difficult. I understand user expectations can sometimes be unrealistic. But let me say this. Take a minute to listen to what your customer is saying. You should be polite and courteous to them as often as you wash your hands after going to the bathroom. If you don't do that 100% of the time, you have more problems then being polite. But I digress.
Your customer is THE most important thing in your job. It's not the process you follow. It's not the product or service you offer. It's the customer. Wait, did I say that? Let me say it again. THE most important thing is the customer. Listen to them. Be polite. Deliver value.