The need for "thank you"

We humans can become so offended when somebody doesn't say thank you for something we've done, some effort we've put forth.

Well, I read some harsh words on the topic that Jesus himself spoke:

“When a servant comes in from plowing or taking care of sheep, does his master say, ‘Come in and eat with me’? No, he says, ‘Prepare my meal, put on your apron, and serve me while I eat. Then you can eat later.’ And does the master thank the servant for doing what he was told to do? Of course not. In the same way, when you obey me you should say, ‘We are unworthy servants who have simply done our duty.’”
Luke 17:7-10 (New Living Translation)