I just got done with a 1400-mi rental stint from Vegas to SF, SLO, and back in an MB GLC300, and there were some "weird" to me things I noticed. It did not have adaptive cruise.
When adjusting cruise speed down in 1mph increments, the car coasted. If you pulled the lever down to get a 5mph reduction, the brakes engaged and the brake lights came on. I believe the Fords I've rented with adaptive do the same thing, in addition to illuminating the brake lights any time the car slows for traffic ahead, even if it's just 1mph that it slows.
Personally, I am very aware of the fact that ANY time brake lights come on, traffic behind you is impacted in a negative way (think: caterpillar slowdowns where there was nothing going on except some JA that tapped his brakes), and people that tap their brakes for reasons that are not related to actually having to slow down, including simply disengaging their cruise control, are a pet peeve of mine. So, when I see slower traffic ahead, or a car is coasting, I coast as well but resist all urges to tap the brakes unless I am actually going to be slowing down a significant amount.
I think that mandating yellow turn signals and red brake lights would do much more for actual safety rather than these other measures, but I also think that the turns and the brake lights should be in the same general location- nothing makes me go "how the F did these Hyundai/Kia/etc engineers ever think that turn signals BELOW the bumper is a good idea?" That location makes more sense as a hazard flasher than a turn signal, especially considering that those signals are most times blocked completely if the vehicle is using a hitch-mounted cargo carrier!