Disliking the mainland is part of Hong Kong's identity. While initially shocking if you go back and forth enough you start appreciating the lesser rules of the mainland and realize that HK is still quite colonial. And while mainlanders won't say "yes sir", or speak English, they are generally quite friendly, curious and genuine. Of course a sense of humor often also helps.
I don't think there is any deliberate malice in it, but consideration for themselves and their family only and solely, is evident and consistent, this aint a bad apple issue. The tour operators and charter flight providers could do more prearrival education in my opinion, fake modern manners for all I care.
I feel very sorry for flight attendants in asia, always a good chat about the subject if sat opposite jump seat