I don't know if any of them specifically require a certain number of presses or such - I've never had an "old style" knob climate system that would automatically turn the blower to max in the defrost position, though that certainly helps the process. But neither have I ever run into a vehicle where the functionality is actively hidden. Scan for the defrost logo, front and rear, interact with the proper controls. To remove this obvious behavior from a car randomly speaks to an insane level of disconnect between the designers (who mostly operate on the concept of change for the sake of change, because any change makes it look new) and users (who, generally, would rather things stay where they were).
I don't care if my car UI wins international design awards for Excellence in Minimalism (ExMn) or something. I care that I can use it to make the various systems do what I want, or put them in a sane "Automatic" mode that then does reasonable things with them. And, further, I very much do care that they don't randomly change on me between trips in the vehicle.
Someone linked the SAE standard in a different comment, but that and the law together basically say nothing about how to turn it on. It only says that you must have one, and how effectively it must perform when on. Then again, both of those are from the late 60s, when computers in cars were still unheard of, physical controls for everything were the norm, and perhaps common sense prevailed a little more...
It’s pretty important. The windshield will sometimes fog up suddenly while driving. The driver needs to utilize extra care and pay more attention looking out a partially fogged windshield at the exact moment that they are forced to go through menus in a touch screen.
If so, then Tesla would need to dedicate one such button to the front defroster regardless of menu state.