RE: Share the etiquette of communication between people in China
This is extremely interesting and please: write more about it!
I myself am somehow not a benchmark for any culture; I have lived in many places in the world and never really felt like I belonged anywhere. But I have developed my own culture and am not willing, for example, to respect someone just because he or she is older than me. One has to earn respect! Conversely, of course, I don't expect respectful restraint from younger people either...
In the 2000s, it was fashionable in German retail outlets to address customers as "you". It seemed relaxed and casual. Confidential. Normal for me - I've always done it that way. The first time a shop assistant said "Thou" to me, I was sure: I'm getting old ;-)) But presumably this fashion was simply over by then and people were behaving more formally...
People all have commonness and individuality. Maybe for some rules and regulations that restrict our behavior, what we have to do is to keep pace with the times and take the essence and discard the dross. Not in every era, and not necessarily for everyone.