WHAT'S THE RULE ON MANILA TIPPING?

At a restaurant in the Lower East Side I once walked out leaving only a dollar behind as tip (huge sacrifice for minimum wage earner me) only to find a very angry Latina waitress screaming after me as I walked away, "No service charge! No service charge!" I found it really weird that she was throwing a fit - because my standard tip here is just P20 - P50 ergo $1. This was three yeras