Re: The non-Hispanic whites
Because governments in the US (state & federal) are concerned about the purity of "white folk" which technically and oddly, as I understand it, includes folk from Portugal and Brazil but not Spain and Argentina. In practice it's a basically a Brownness Scale (B.S.) to determine if you're special in some way. Note that there's almost always another box marked "Hispanic (any race)" to double down on the B.S. in an attempt to be more
I used to try ticking a box that I hadn't ticked before but as I rapidly approach the age of dirt I think I've already ticked them all at one point or another so for the last census I wrote in Inuit+Zulu. Let's be honest, they don't really care and they aren't about to call you on it. "Honest, it's what my parents, Akluitok and Anele, told me!"