Yes, there are mods out there that make GTA look like a photo-realistic adventure: https://www.youtube.com/watch?v=7cbL3HUqAJU

A more than four-year-old videogame, yes.

on last generation hardware too, though the screenshot in question might be taken one of the ports to more modern systems

It's from a computer, not a console.

Look at the white brick pillars in the background behind the car; they're exactly the same. Some other stuff like the soda bottle pops out as well. It does look nice though.

I don't know if there's supposed to be some depth-of-field effect going on here, or what, but I find it really jarring that the resolution of the textures applied to objects in the scene are so different. The car and that one section of wall are super-sharp and high-resolution, then right next to them some of the trash is fuzzy, blurry lo-res textures.

In this case it seems it's some sort of DoF-Effect, since the lines between the objects seem to blur too.

well, yeah. do you have any idea how massive the world map is in GTA??? Of course they have to scale the textures.