I don't know that epoxy coating is used at the municipal level. Pipe bursting with high-density polyethylene is the typical solution to avoid re-trenching municipal sewer pipes. Epoxy liners, epoxy coatings and polyurethane coatings are typical for a single property.

I would argue pipe bursting is the best trench-less solution for any place, but it is more destructive than those other three options.

I had my residential waste pipe lined with a fibreglass/resin sheath about a year ago. Inserting it was a process involving a lot of work on endoscopes and then the liner itself was adhered to the old pipe using a bladder filled with hot water. See: https://en.m.wikipedia.org/wiki/Cured-in-place_pipe

It was over CA$10k to get it done, but the cost of trenching that line could have been 3-4x the amount + an unacceptable risk to the foundation of the house from destabilizing the dirt around it.

I know epoxy coating is used in large hydro power dams, so I have to assume it's used for municipal sewer lines as well.

It's somewhat funny because most epoxy is just straight BPA. Yes, that BPA.