Did the plumber pull any sort of permit to do this job? If so then they will need to have an inspection done. Beyond that, they are just doing you a good service I'd have to say.
Each city has slightly different requirements when it comes to permits and inspections. Assuming the work was done in Chesapeake, it is my understanding that even replacement of an existing electric hot water heater requires an inspection; it is not a requirement in Virginia Beach. If it is a new installation, or it is being relocated, or it is a gas hot water heater, inspection is required in both cities. The type of inspection required (electrical, plumbing, mechanical) varies with the installation.
All things considered, your plumber is doing the right thing.
I am in Chesapeake, VA and this is our third water heather in 9 years.! The first two replacements no permit was requested. However, we are members of a home warranty now , which the current plumber requested the city inspection after the replacement.
That is unusual that you went thru two heaters in 9 years. Hopefully three is a charm...:) Tim