Basic numbers are, as an SO joining now you get 10K/month that will not rise, as an SO. Expats get 60K+/month tied to the government index, rises and falls with the market, locked in for two years when you rent or buy.
Yes if a local joined through the cadet scheme they would get the cadet package.
The reason for this is:
The had 0 experience when they joined
Hong Kong is their home, they are not moving away from home to work.
Expats get a good housing deal because:
It is what is required to get quality experience to move half way around the world to fly your planes.
Most guys who joined as DESO on expat terms had well over 3000 hours, many with a lot of jet time, many ex military, almost all with at least turboprop command time.
Competition was fierce and CX could choose who they wanted.
I am not saying I agreed with the housing deal for locals which until recently was 0. I firmly believe that once they are experienced they should be given a better deal. They pass the same checks, jump through the same hoops, fly the same planes. Many of the local guys who have now got experience are looking elsewhere for a better deal.