Yeah they're not all red, but they shouldn't be white.
I haven't seen any strains with white hairs in the good and proper end product.
Even the supposedly "albino" strains just have like light red/pink, or light orange/red hairs.
Some hazes have "silver" hairs that I've seen. But they're really just really light, trichome covered hairs.
If your only gonna use one factor to decide when to harvest, then you should go by the color of the trichomes, not the color of the hairs. But really it's more about reading your plant, the trichomes, and the red hairs.
Like ten, twelve years ago ppl used to harvest when 60-80% hairs tuned red, or something, but now it's more about the trics.