To me, it looks like just typing in "wacky psa" in the eBay search field will show you only cards in the "wacky packages" category. While that 6-up is in the "vintage non-sport" category.
Although there's no indication that you are only seeing results from a sub-category, and it appears that you are in the broader non-sport category.
I think it's a "smart search" type of thing, where 'best match' is hurting your results.