no offense, but if I'd hear someone playing covers with an arranger keyboard, I would not feel compelled to give applauses. This is not because I am mean ,or because I am diminishing your job in any ways.. I would simply assume that you are doing your job, no more and no less.
Maybe I am wrong, but I think that the audience perceives the above in the same way. I don't think they meant to be nasty. Personally I respect an audience like that. I can't stand an audience who gives applauses like monkeys every 3 seconds for nothing. In some settings, like classical music concerts, this happens often. I can feel that people applaude out of social requirements, rather than because they really want to applaude. They also do it out of habit. I think that sucks.

Especially rich people, do you think they give a damn.... they can get a lot by just giving directions; they simply thought that they are paying for a service (and in that, I can't fault them).

But in the end, you are right, what do you care, just be as pro as possible. It's not worth wondering what other people think of you or why. It's their bag, who cares. Don't even hate them, as it would show in your profession.