When the context is involving climate, electricity rates, and money, there is little overlap between all of the Americas. It makes sense to tighten it down to the top half (more similar climates, etc) or bottom half (electricity rates for example). Canada has the wealth and the electricity rates to make heat pumps extremely viable, and for the most part climate too. The USA shares a lot of this. The Central/South Americas do not overlap like this with Canada.

But that wouldn't be accurate because there are South American countries with even cheaper electricity than here, so it's only the cheapest in North America.

Also not to be too pedantic but central America isn't technically a continent, and it all falls under North America anyways.