When I realize the car or truck ahead of me is emitting something I don't want to breathe (either because I see it coming out the tailpipe, or because I start to smell it), I want to switch to recirculation RIGHT NOW, not after I navigate through a maze of menus that require me to take my attention away from driving.
Also, I want temperature regulation based on how hot or cold I feel, not what some thermometer says (and often have different opinions about where the air should be blowing depending on how I feel).
They're just following John Green's policy on electricians and witches: "If you don't know how to do something well, hire someone who does. My policy is that I don't change the wiring in my own house, and I don't hex my own enemies." (https://www.youtube.com/shorts/mxdwS3f209E)