Yes, the claim is that living in a warmer climate and using A/C to cool 10-20 degrees in the summer is more energy efficient than living in a cold one and heating by 40-50 degrees in the winter.
You can change street design and work on public transit because those are things we built. You can't change where people live without displacing them. Just like you said, not existing would save the environment too, like bulldozing every spawling suburb and exhurb in the US would save a lot on GHG but it would be pretty cruel.
So you aren't going to fix anything with expensive passive houses. Especially since passive houses need major repairs every 10-20 years.
What's needed to to ban gas and oil fired furnaces and make the grid 100% renewable. Everything else is a distraction.