Those slabs are referring to the white letter on the back, not the white letters on the front. The PSA slab that doesn't mention it is just a card that was graded before PSA acknowledged the variation. All three cards in those scans are exactly the same (except for their condition) and are the only known version of Jeter base card for the set.
What we're slowly piecing together in this thread is that, as it turns out, there is no variation for some of these base cards (like Jeter) and for the base cards that do have a variation there is no rarity attached and hence no value premium applied.
Arthur