Oh I love being the one to correct them. I have done it several times here in Visayas (my command over the Visayan language is improving) and they always get this deer in the headlights look. In fact I never pass up the opportunity to point out when someone ignores common courtesy. It rubbed off on me from spending time around Japanese guys. I coulda swore it almost got me killed in Colombia a couple years back when I saw a couple of kids around age 18-20 not give up their seat to an old couple at a bus station. They could have easily pounded me to shit, these were tough looking kids. It took em a few seconds to make sense of me telling them to get the hell up and asking what is wrong with them. Then they got up and actually thanked me for correcting them.
Anyway, point is, Colombia is a poor country with old traditions, like China was before the great leap backwards. Now, when ever you see a mainland Chinese person, they're almost invariably doing something that shows complete lack of courtesy. It's really a backwards society and it's contained to the commies. You don't see it in Taiwan, Hong Kong or Singapore.