Most people, and you can understand why given that it's a municipal service, think that a municipal sewer line is the responsibility of the municipality/town. It isn't unfortunately.
These lines over time warp, corrode, become blocked or forever damaged by tree roots. Fixing the problem can cost thousands of dollars. Picture calling the plumber, having him or her determine the problem and informing you the line has to be dug up from house to street and replaced. You are also responsible for patching municiple property, i.e. the ashpalt.
If you're buying a home in the Annapolis Valley of Nova Scotia you'll be facing sewer lines made of cast iron, no-corrode, clay and plastic. If you see a beautiful tree on the property, panic. They love water and will go to great length's to seek it out which includes invading the sewer line.
What do you do? You have the sewer line inspected by a plumber who has a high quality video line to run down the pipe. You'll see the actual footage (video) of what's in that pipe. It's well worth the few hundred dollars.
The older the location as in the gorgeous century homes in Wolfville, Kentville and Annapolis Royal, the more likely you'll find corrupt pipes.