Because with the angle of the front bumpers, the squatted trucks will activate emergency braking only/ and every time a cessna or piper cub flies over head. It would not sense the cars in front.
For that matter, I'm going to guess that these adaptive cruise systems are designed to operate at the stock ride height.
Even with a "regular" lifted truck, we already know most owners don't bother to re-aim the headlights. I'm reminded of this now that it gets dark at 4:30 at it's rare I make a trip home from work where I don't get blinded at least once by 6"+ lifted truck glaring their incorrectly aimed HID/LED headlights into my rearview(and for whatever reason the auto-dimming feature either not working correctly with them or it just not dimming enough to counteract this).
If a truck is lifted at the front by several inches or more, do we know the front sensors that are involved in things like adaptive cruise and braking will work correctly(or need to be re-aimed)? I'm GUESSING that these probably use bumper/front end sensors not unlike the back-up warning ones in my rear bumper, although I also know newer cars have cameras and other sophisticated systems involved that work into this.
Still, though, if someone can't bother to reaim their headlights after adjusting the ride height, whether it's a "flat" adjustment or worse a squat, why do we think they would adjust the other systems?
For the record too, here's my general though on car modifications-there are a lot that in my personal opinion look stupid, like a park bench on the back of a front wheel drive economy car(haven't seen one in a while) but ultimately don't hurt anything. When you start modifying in such a way that it directly impacts my driving, such as glaring your headlights right into my mirrors or changing your suspension such that your handling is unpredictable or even unsafe and you can't make evasive maneuvers, I do care about it. BTW, the handling thing doesn't just apply to lifts or squats on trucks, or to 80s boxes riding on 24" wheels that have to be raised a foot so that the wheels fit, but also the other extreme where a car gets slammed and then the camber adjusted extreme enough that you only have 2" of tire contacting the pavement...