In my experience the U.S. seems to tend to want a form officially affirming I am not from the U.S. and further something about how much business I actually do in the U.S. or how totally I can really claim to not be U.S. or something like that. That might have been about some other form than the one discussed here but was something someone did need for me to do business with them due to they themselves were in the U.S.
-MarkM-
I know with commission junction and other types of sites they get you to fill out that form.
Its like they dont want anyone investing in the country ....