To answer the ATi question, it's because ATi use Brilinear instead of Trilinear so that it makes their cards look better compared to Nvidia's.
Not exactly. Note that NV has trilinear optimizations enabled
by default, and most reviewers have been testing the NV cards with tri optimizations enabled. One of the real issues here is regarding anisotropic optimizations. It seems pretty clear to me that ATI is using both trilinear and anisotropic filtering optimizations by default, so one would think that it would only be fair to bench against the NV cards that also use tri and aniso filtering optimizations enabled in the driver. However, before that can be done, a detailed image quality analysis using pictures and in-game visual quality inspection should be done that compares ATI's optimized modes to NV's optimized modes.