My new laptop has a 3:2 high DPI screen (3300x2200), but for a game like this I'm just running at 1080p because otherwise the UI is too small. I have my video driver set to preserve aspect ratio and it works great for everything except Banished (so far at least).

Normally, if I set a full screen game to 1080p the game will switch the video mode to 1920x1080 and then the hardware will scale that up to fill the screen with a bit of letterboxing.
In this instance, setting the game to 1080p doesn't seem to change the system resolution at a hardware level, but instead renders the game at 1080p and then software scales it up to the desktop resolution with no regard for aspect ratio. The video driver setting has no effect because as far as its concerned the computer is still running at 3300x2200.
The workaround I've discovered is that DX9 changes the system resolution as expected, but if anyone has any explanations for this bizarre problem I'd love to know.