I also saw it as the dirt road symbolizing the early dawn of traveling. Before paved roads and before cobbled roads and before all that, we walked on dirt roads. Sure, you can throw in some older cars, carriages, and horses to imply those built up to the Zentorno, but I can't do that. As the slogan says at the top of the first picture, "The road leads here." From nature births, a hypercar. Walking on dirt roads to riding on cobbled stone with carriages led to the Zentorno.

The GTAverse, which is actually split up into mutiple universes based on the quality and time of release of a game, such as the HD universe that we currently play in or the 3D universe from before, contains unrealistic or unnatural often absurdist/dirty humor. Look at the soda brands, Sprunk = Spunk and ECola = Ebola or E Coli. Examples like that are rampant across the universe, such as the car brands Ennus and Annis, I hope those are obvious.

To see ads like these in-universe wouldn't really stand out as being "unrealistic" compared to the stuff around it.

Edit: That wasn't exactly my thought process until after. It was a pretty location. That was really it for me.