It's been a problem with rentals... the old Mercury Stats would last a lifetime and very reliable for Millivolt systems too!
I've gone from never having Stat problems to having them... tenants have on wrong setting, remove batteries, etc...
With the Heat Pump units they freak when the temps drop below freezing and Auxiliary or Emergency Heat is indicated... always get calls saying the system needs to be checked when the January Electric bills hit.
Aside from the tech/reliability issues, you also have the same key issue I now have to deal with - sky high electricity rates, that show no sign of slowing down, or should I say Up.....
That trajectory has removed all-electric from my future plans, at least when on-grid.
I do like ground or water-sourced geothermal as a technology just fine though - my issue is where I live, legislation wise....
Rgds, D.