I'm sorry, but that's not the case, and you are confusing two very different things:
1) A difference between asphalt and concrete textures, which the thread was about, and it's also what has been shown on your screenshot.
2) The fact that not ALL photoreal background scenery is covered by the detail texture.
In the first screenshot you posted as an example, to show an area of sharp and blurred textures together, we see an area where concrete meets asphalt and, I repeat and confirm, there's NO DIFFERENCE in anything, resolution or coverage, between the two. The ONLY difference is which detail texture has been used on the top layer.
Your coverage example is not fitting because, it assumes that the scenery was made with single textures covering different area sizes.
But, the scenery IS NOT made like that! The concrete you see in your 2nd set of screenshots is made using two layers: the "color" part, the one that gives the subtle grey/yellowish basic tone, is coming from the BACKGROUND photoreal texture, and it's the same texture that you have posted in the other screenshot, to prove the point of the different area/pixel ratio, as to explain the blurrines...
Instead, on TOP of that "blurred" texture, there's a detail texture, which only includes the visible features, like the pavement joints/cracks, overlayed on top of the lower res one.
The asphalt texture, that was shown in your 1st screen as being supposedly blurred, is made in exactly the same way, using the same method, just the colors are different: the basic dark grey comes from the background photoreal, and the small grains come from the detail texture. If you look very closely in YOUR screenshot, the grains ARE visible, even in the part that is supposed to be "blurred"
The issue is just that: that detail texture was probably too subtle, the grain was too fine and the alpha was too thin so, as soon as you raise a little bit over the ground, it just gets lost and it's not possible to see the detail anymore, so you are left with the much lower photoreal background only.
So, as I've said, the whole difference lies in detail textures, and it could be easily proved, by using the replacement texture I've posted, that is more visible and doesn't disappear so soon.
THEN, we have fact N.2, which is: detail textures are not used everywere, but only on areas were you are supposed to be with the airplane. Basically: every paved surface. Grass, for example, is made just with the photoreal background. But, nobody complained about grass, and your screenshot shows two paved surfaces anyway so, we were discussing about issue N.1