AFAIK the physics of heat pumps is considered to have been fully figured out for ages and all that's left is the engineering. Maybe it wasn't considered a "sexy

AFAIK the physics of heat pumps is considered to have been fully figured out for ages and all that's left is the engineering. Maybe it wasn't considered a "sexy" enough topic to nerd out over and hyper-optimize? Edit: it might also be an issue of diminishing returns of better efficiency compared to how difficult it is to produce and maintain a better unit. Thermodynamics can be a pain like that.