I'm never upset. I just cannot believe that you are not considering what the inside of a water heater turns into over years, how it lessens in capacity, how it makes it so hard to transfer heat whether by element or burner.
If you only knew how often I come into homes with thermostats cranked up well beyond the 120 degree setting and they're telling me they keep running out of hot water...and I've checked to make sure it doesn't imply a failing dip tube scenario...it proves the tank has lost its true worth as a working unit.
But people weigh the fact that it isn't leaking as a primary move to switch out. Rarely do people change out a heater before it leaks. I do them, and if you saw the condition of some, you'll know why they are pleased with the recovery of the new ones.
I've got some great knowledge of water heaters and a slew of situations like other plumbers have on these sites, but what you're gauging is something that doesn't guarantee efficiency of a unit. Look at tankless heaters for example: you have to keep those compartments delimed/descaled or those numbers are just junk science for those who compare therms or kilowatt usages.
One thing I will not do in plumbing is build false hope. Even though I instruct my customers to drain their water heater once a year, the reality is that water heater loses the cost per annual year first number rather quickly, depending on water quality.
If they made a water heater that defied water quality issues, you could definitely produce a list like you have going, knowing the efficiency isn't compromised.