The problem is not laying down fiber or building infrastructure: The problem is that nobody else can because of contractual agreements. [ ... ]
Well, yes, that's part of it, but there are other hurdles as well.
For example, one of the reasons Kansas City got picked is that the municipality owns the poles. More precisely, as I recall, KCK owns all their poles, and KCMO owns many (most?) of the poles, with the rest owned by AT&T.
Another "problem" is local environmental regulations. I put "problem" in quotes because avoiding unnecessary environmental damage is a laudable goal. However, accomplishing this goal is usually a huge pain in the butt -- EIS reports take months to compile, and then can be challenged by essentially anyone for any reason. Where and how are you going to trench? Are there any legacy pollutants in the dirt? How will you handle that? What happens if you discover a culturally significant site while digging (e.g. Native American burial ground)? Will you need to disturb the protected osprey nest sitting on the seventh pole along the 400 block of Horton Street? What kind of fiber bundle are you pulling? Will it leach toxic materials in the heat/rain/snow? How much noise to you intend to make while doing this? Will the city have to re-route traffic around downtown while you're trenching?
So, yeah, it can be a huge pain in the neck even without factoring in whiny incumbent competitors.