Why are there no new full-fledged roads? When I searched for them on steam, I found only various road retextures. And this is good, but why are there no mods that add new types of roads?

It would be nice to see full-fledged autobahns, on which there would be no speed limits (well, or a limit of a very large value). Or old cobblestone roads for the historic districts of cities.

Of course, I suspect that installing such mods will require manual installation in the game files themselves, but even with such restrictions, I did not see mods in Steam.

So I ask the community, what is the reason for their absence? And is it difficult to make them yourself, or are there any pitfalls?