The main problem is organizing. Legal and technical problems are easy by comparison. I wrote a guide here for starting your own network- https://www.nycmesh.net/blog/how/
My quote was a bit out of context. I was talking about how if it rained my old Time Warner Cable ("Spectrum") connection would go down for a day. This is a known TWC problem in downtown Manhattan.
NYC Mesh is having a different problem with very heavy rain where two of our high speed point-to-point connections (60GHz and 24GHz) will go down for like 20 minutes in very heavy rain. We're working on fixing this.
Yes, I don't think Verizon would peer with us, but we peer with some very large companies like Google, Apple, Akamai. The full list is here- https://www.nycmesh.net/peering
Supernodes are connected by fiber so they can be any distance apart.
The two main areas we have connected are the Lower East Side and Chinatown in Manhattan (mixed income) and in Brooklyn our main hub is in a low-income housing association building, definitely not a "richer neighborhood". It is a priority of ours to get to the neighborhoods that need us the most.