Interesting question… what do you think about using structure assets for roads? Structure assets can be locations, too!
It would be nice if we could formalize the concept of roads roads though because it is quite common and could be one less complexity for users to “wonder” about. I agree that roads should normally be fixed location assets but not sure on land vs structure… There is likely an argument for both and not a right/wrong answer, but IMO without a dedicated road land type I think I might lean more towards using structure assets.
This is partially because I’m thinking about the drain structure type we added for Rothamsted Research: Drain structure issue + discussion and the resulting Drain structure config. In this case the “Drain” is interesting because it is both (I assume) physical infrastructure but also a piece of land that is managed like other types of land (mowing, spraying, etc). In that issue we also mention adding “Road” structure types as well but ultimately “we discussed that we could add additional types in the future, but there should be some thought & reason before everything [on the property at Rothamsted] gets mapped & added to farmOS.”
I think I consider structure as “infra-structure” more generally and would prefer to keep things separate from “land” when possible. The idea of “storage locations” is interesting though. If I had a piece of land without physical building/infrastructure that was only used to store things on I would probably create a field/other land asset… although if I thought about it long enough I might just end up making it a structure asset too 
Maybe there is a use-case for asset categories here 
Cannot categorize assets with a taxonomy