How many Anglo's between ages 19 to 23 would actually hold a HKID card , I would say under 1000 , more likely under 500
Something tells me your figures would be quite off.
I went to an international school where the majority of the students were
of non-Asian race and the majority had permanent HKID cards.
Do not forget Hong Kong wasn't owned by china pre-97, still a lot of, as you would say, whitey's, growing up with HKID cards and who knows, some may stay and have white kids who will in turn own an HKID card.... and so on.
Don't forget that the non-HKID holders who went through the interview process were still being selected or were awaiting for the course to start. I could be completely wrong but I believe the HKID card rule was to stop the initial process of new applicants.
Saying this, no one has any right to complain about Hong Kong making their own law's. Surely if a country like Australia can refuse you because you are not Australian, Hong Kong should be able to do the same.