The fact that some people with pale skin and light features experience does mean it's problematic to use "white" as a synonym for "does not experience racism".

But this is also true in America: there are pale south americans of largely european extraction who get classified as "Latino" while spanish immigrants do not (though they will still experience racism from people who judge them on appearance and accent alone) So it is at best a useful shorthand, and it's important to remember that people who are "white" in one context are not in another.

And yes, it's complicated, and it's important for us non-europeans not to barge in thinking we understand it all. But if they find use in american terminology (and from what I've seen some of them do) I don't think it's our place to tell them they're wrong either. We can sit here arguing from the sidelines but to be honest I'm not sure it matters.

(Which is to say: I'm not sure this tangent has a lot of point, given we're all a bunch of australians working off second hand information)