I'm glad I grew up where it's about the same level of rudeness as HK so it doesn't bother me. I think after the SARS scare some people are pathological about not touching doors and such if they can avoid it.
I will still hold the door open for the next person but I don't expect a thank you or anything like that, I think I wouldn't get one in a lot of places in the US when it's as crowded as it usually is in HK.
Also, I cut some slack because some people panic when seeing a foreign face and are afraid to say m'goy and are also afraid of their English so say nothing. Yes, some people are being rude but more are clueless, scared, or too busy looking at a phone. When I was younger, I took things more personally, but now I think I more philosophical. I realize most people are just clueless or could care less...
My father never really adapted to the lack of politeness compared to home and retired (and died) back in Tacoma, WA.