OK I had a look at the immigration stats and it seems only 35000 tests have been done at immigration since the mass testing policy, but 96000 tests have been done throughout HK.
So I am happy to admit the numbers aren't as skewed as I thought. Although this is still a significant proportion of tests (over 1/3), it isn't high enough to explain why the majority of new cases would be imported.
HK has indeed increased their testing throughout HK and not just at the airport. So I was wrong there regarding the extent of the test percentage done at immigration. I still feel the figures are skewed somewhat but I guess they always will be.
Now I've admitted I was wrong I think I had better logout since I don't particularly want to read the smug responses