Why do I bother trying to be nice?

This happens almost every time I go out to shop anywhere. Now, I spent the majority of my working life, working with the public so I know first hand that the public can and often does stink. However, having been "behind the counter", I always try to be nice to the cashiers, sales people and waiters of the world. It seems as of late my civil gestures and use of good manners results in nothing but grunts and mystified blank looks.

For example, yesterday I went grocery shopping at Shoprite located at 1054 Old Country Road, Plainview, and encountered a robotic human male functioning as a cashier. As I finished placing my goods on the conveyer belt I approached the "gentleman" and greeted him by saying, "Hi, how are you today?". This lifeless being replied by saying in a monotone voice, "Shoprite Card". For some reason this day in particular I was not in the mood to be dismissed in this way and lectured the robot on what it means to be civilized and polite. He responded by saying nothing (and spitting on my bread in a very human fashion). I had made an attempt to be friendly and pleasant yet he was only able to respond in the way he has been programmed to by the big dogs at Shoprite who are intent on profiling their customers. Why is is suddenly "okay" to be so rude?

I wish I didn't hate those self check out things so much as I find the level of humanity coming from those machines to be much easier to deal with.