Nope, it’s all about the temperature differential. Using a heat pump like an air conditioner is the same efficiency either direction. Usually when you’re talking about heat it’s going from (say) 20F to 70F, with AC it’s more like 90F to 70F. With heat you might even need to do like 0F to 65. AC max might be 115 to 75 which is still substantially less.
How about building design? I know in colder climates buildings are designed to retain heat. Are buildings in warmer climates designed with similar heat insulation in mind? I think traditional architectures are designed for convective cooling but that doesn't play well with air-conditioning. Not too mention the modern designs obsessed with glass which I think traps heat. Good and efficient for cold climates, not so much for the hot ones.
