All networks, including us, add to this expensive infrastructure. The difference with our infrastructure is it is owned and shared by members.
So the main thing holding you back is time, money, resources, access, customers, and logistics?
A bunch of businesses and nonprofits offer free wifi to their customers, and over time you build up a big enough blanket that pretty much anybody can walk into a coffee shop or library and check their email.
Tons of security risks, of course, but... I mean, I've used public wifi before during personal emergencies, and I was pretty grateful it existed. If you're gonna pick a comparison to be derisive with, maybe don't pick something that's widely useful and appreciated?
Comcast has even turned this into a selling point (I think somewhat unethically) by turning all of their customer access points into semi-public routers for other customers. It actually seems to scale pretty well.
Comcast provides its wifi by allowing you to connect to any other customer's router. (Roughly) a mesh network provides its wifi by allowing you to connect to any of the other nodes within the mesh.
What's your point? Is the money/infrastructure less legitimate because it was donated? Is the public wifi down at the library fundamentally worse because its cost wasn't bundled into the price of a coffee?
Hardware is hardware. If it works, who cares where it came from?