I think it boils down to a) effectively storing heat for later use is extremely difficult to do well, and b) moving heat around properly means 400psi compressor tubes everywhere, and those are a lot more fragile and annoying to work with than regular plumbing, and you need a special gas licence to charge them up afterward.

In contrast to the RV proposal, maybe a better option could be something like a boutique hotel, where you’ve got 100+ showers happening every morning, so having a giant cistern of hot water that you dump all the waste heat from AC, fridges, and freezers into makes a ton of sense.

"I think it boils down to..."

Nailed it.