The regulation calls out 19 vehicle functions which must have physical controls inside the vehicle, with additional requirements about size and usability of the buttons.
Those functions include:
Turn signals
Hazard lights
Horn
PRND gear shifter
Driver assist function, if present
Windshield wipers
Windshield defroster
Power windows
Emergency call system
Power off switch for EVs
Not a single car I’ve had has gotten the auto temperature control exactly right. It’s quite normal for me to set it to 16 or lower in the summer and 24 or so in the winter, but in addition to that, I’d usually have to adjust after like half an hour of driving because now suddenly the 24 is way too hot.
Climate control (not the AC button, but the system in general) is probably the one non-essential feature I touch the most in a car, with infotainment being second as I tend to just set it and forget it (radio generally).