RT2012 is the reason my uncle installed a reversible heatpump to replace the cheap electric radiator in the house he renovated, so i'm not sure it's really forbidden. But yes, RT2012 make building new houses more expensive, and you don't want to add a AC unit to that. Especially since most areas expressly forbid visible heatpump from the streets, so you have the added cost of having to hide them (In France, we basically have a big HoA in each city, it's called PLU and the mayor get to choose the color scheme and maximum height of your house, the maximum height of your trees and if you get to have AC or not).