To quote from the blog post:

> Unity has a package called Entities Graphics, but surprisingly Cities: Skylines 2 doesn’t seem to use that. The reason might be its relative immaturity and its limited set of supported rendering features

I'd hazard a guess their implementation of whatever bridge between ECS and rendering is not capable of LODs currently (for whatever reason). I doubt they simply forgot to slap on the standard Unity component for LODs during development, there's got to be a bigger roadblock here

Edit: The non-presence of lod'ed models in the build does not necessarily mean they don't exist. Unity builds will usually not include assets that aren't referenced, so they may well exists, just waiting to be used.