While that's true in colder areas where they aren't as useful, in milder places like Vancouver, heat pumps (as they're called in North America) do have some market share. One report I saw estimated there are 700,000 residential air-source heat pumps installed in Canada (against a total number about 15 million households, so admittedly a small market share, but it does exist). More detail: Heating and Cooling With a Heat Pump
