For me it's the opposite - if people aren't bowing/curtesing I feel even more obliged to do it, to set an example.

And I didnt? How impolite of me! Well, it was a long time ago, and in those days I mainly curtesied to old people, while younger ones always found it weird and funny. Then I decided that I didnt care what they thought as long as I followed my own social behaviour-compass (and also found out how fun it is to annoy people through pure politeness).