the last time i worked in hk, my employer was able to skim the first year of MPF as they were legally entitled not to contribute for any 1st year joiner, even though my contract was a permanent one.
took this from the mpf site: "
if your employment visa allows you to remain in Hong Kong for 13 months or less, then you are exempt from joining an MPF scheme.
In the event that your employment visa is subsequently renewed, bringing your total continuous period of stay in Hong Kong to over 13 months, you would cease to be exempt starting the first day after the end of the 13-month period. Your employer will then be required to enrol you in an MPF scheme and make mandatory contributions accordingly."
I guess then most expats came in with a 12mth first visa, so all gets exempted by the employers that are calculative.