Does anyone else feel like most "white passing" people don't actually look white even though other people say they do?

I will see people online say they are white passing and then when I click on their profile more than half the time they don't look white at all to me? It's kinda confusing and baffling to me to see mixed people call themselves white just because others do when to me I can clearly see they are mixed. Maybe people just aren't well traveled?