Unfortunately the percentages are accurate, i'm more inclined to believe we are simply suffering from confirmation bias
I've noticed that, at least for HQ percentages, it is pretty much accurate. When mining the HQ materials I need, particularly for the class quests, I keep both the NQ and HQ items in my hotbar, to better keep track. After i've raced up the correct HQ materials i'd end up noticing that the rate of HQ is roughly 18% of my total. Considering I use the +10% HQ Chance ability as often as I can, it makes sense to be skewed upwards.