I've done maintenance and would gladly take the preventatives like changing an anode rod instead of fielding calls for toilet clogs and pulling dentures out of disposals! But that's someone else signing my check.
As I homeowner I would gladly do it knowing that the best place to hide is behind a water heater, come out smelling like sulfur and earn myself a free Saturday to spend in the garage. I wouldn't make it a priority though.
If it's a flip house, it would be getting a new WH, used for two years and moving out before the warranty ends.
Interesting question, the more I think about it. Totally understand your point and the logic behind it, but I don't see the financial gain, or the longevity in our disposable manufacturing environment we currently live in.
$150 for the furnace seems like a great deal until it's broken down. I assume if any actual repairs come up those are out of pocket? And they almost always find something that needs to be repaired?!
If I tap into the mentality of my paycheck to paycheck millennial counterparts, and assume that stoves and dryers will still last forever: