Very few first time buyers get a sewer inspection. Usually this is because sewer inspections are not top of mind. Sometimes it is because buyers assume newer homes don't need a sewer inspection.
Recently a new purchaser (2nd owner) was having back ups problems with the sewer; he did not get an inspection before he purchased.
In the video below the inspector found that a piece of re-rod used to stake the foundation had been driven down through the sewer pipe. This problem was contained within the walls of the basement and was only visible using a sewer scope.