When that GT7 pic was taken the camera is moving, you can clearly see it panning in the video that screen grab was taken from, it is also not focused on the trackside.
Like I said, anyone can pick a bad picture of one game and a good picture of another to make their point. I can take a static picture of my garden from my living room and blur the french doors and curtains using nothing more than autofocus.
Those GT7 textures are likely only blurred because of the circumstances of the shot, they will likely not be blurred if you stopped your car facing them in 1st person view. This shot is from more of a distance but you can clearly see the textures are detailed and not blurred:
And before you say "ah but that's a promo shot" so it the shot you provided of ACC, not only that but it's from the PC version, so no wonder all of the settings are turned up to max.