With my two most recent RVs I have never had a problem with the Grey, Black or Fresh Water Tanks. My current RV is 20 years old and the one before it was 16 years old. I wouldn't consider the grey, black of fresh water tanks as a “wear” item. My expectation as well as most manufacturers is these are permanent fixtures to last the life of the RV. Hence the inconsiderate engineering.
That being said... If I had to replace the tanks on either of these RVs it would have been difficult without removing drivetrain and suspension parts.