I’ve watched many heat pump videos from Technology Connections on YouTube and he covers some of this. Heat pumps have had trouble handling really cold temperatures (apparently they’re getting better at that), so rather than having a furnace and a heat pump, or just a heat pump and being left cold… most Americans in regions that need to worry about being colder than heat pumps could historically handle would just get a furnace and call it a day. I’m in one of those areas. I’m starting to see heat pumps around on newer builds, I assume due to advancements in the technology. The Technology Connections guy tried it out and clocked just a few days per year that the heat pump wasn’t good enough. Some people are willing to put up with that, some aren’t, and most are going to assume it’s going to be worse than that, so they play it safe. Everyone has a pretty big fear of their pipes freezing (rightfully so).