Our town sewerage was installed mid 1960's - I'd just left school end 1960. -  getting close to 60 yrs.  Country Aust.

Now some originals have been given the epoxy insert treatment, others have been totally replaced. But the replacement is mainly by boring underground, and only digging a hole where a home outlet has to join the main line.

From the 'mix' of treatments I surmise that there is some physical examination after a problem is detected. [Don't ask me how!].