To tip or not to tip?

I had a coffee with friends at one of my favourite places today. I know the owner and I know most of the staff. They are great and the coffee is good. The most popular are the delicious, home made cakes that are made according to the secret recipes of the owner's Italian mum prepared by her own dear hands. I appreciate good service and good food so when I get them I like to leave a tip. Today we sat around longer than usual after finishing our cake and drink, chatting. We paid for our bill and left a tip on the table. After saying good-bye to each other with my friends, I was just about to drive away when I saw the waitress cleaning our table but not seeing and taking the tip we left for her as a thank you. Our table was on a busy pathway and we were worried that by-passers would just take the money so visible. We decided to give the cafe a quick call. Soon the waitress came out to check the money but for the time she got there a few people sat down at the table. The waitress picked up the money and left.
This situation made me think about how many times after giving tips to people I hear no thank you or see any form of sign of gratitude. What does that encourage? Not leaving a tip! It is a very simple example of how important it is to be grateful for everything we get!
What are you grateful today?

I am grateful that I woke up this morning, that I am healthy, that my music teaching business goes well, that a friend thought me worthy of asking me to work with her and promote new products in Australia that is a huge business opportunity, that I have lovely students and parents to work with, I am grateful that my brother is healthy and happy and that we are working pour business together, grateful that I have great friends.... and that I am doing what I love doing!