Oh interesting, I think I conflated two things; Selective Availability and the military-only bands on GPS. While it's true that access to the military band could improve accuracy with dual-band receivers, consumer devices can use dual-band as well (as your link shows), since there are multiple unencrypted bands from navigation satellites nowadays.

I am not sure how to interpret your link, though. It doesn't measure accuracy on it's own, and doesn't include a number for precision between the two units.

My understanding is that the encrypted military-level GPS is much more robust against jamming and spoofing. There's probably a lot of capabilities we don't know that's classified, too.