My sister lives in a town in Massachusetts with community-run Internet. She's always freaking out about broadband caps, violation of which apparently triggers massive fees.
Is the internet truly municipal or is only the fibre community owned? The distinction is important as a lot of private ISPs pay the local government a fee to use their existing infrastructure, while they provide the connectivity to the rest of the internet.
This arrangement also comes with the ISP's own flavor of EULA.
Can you elaborate on which town and who provides the service? The example above you cited Chattanooga and epbfi.com website that basic service costs $57.99/mo for 100 Mbs internet with no reference to a cap. Your comment seems disingenuous that you don't provide any details.
The linked article mentions that by Oct, 2013, the price for 1Gbit from EPB was reduced ~$70/month, and the folks who were paying ~$58 for 100mbit got bumped to 1Gbit at no additional charge.
Except for the useless "Lite" level, their bandwidth caps are up in the hundreds of gigabytes. That sounds pretty typical. Unless you are a photographer or videographer moving workflow or backups over that account, your not going to touch those caps.