I think it's the fuel pickup placement and the tank design. Take a look at this diagram:
172 Fuel Tank :: Fuel & Engine Control :: Genuine Nissan Parts :: 370Z Parts (Z34) 2009-2011 :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com
From reading the fuel starve thread it just seems like the pickup is at the front right of the tank, and given the tank design fuel can run away from the pickup even when it's darn near 9/10ths full if you are in the "right" type of right hand corner. Seems like you need to be on R Comps to successfully starve the pump at 9/10ths, though.