I think the headrest issue is a conflict between comfort and safety. For safety, the head should be in contact with the headrest upon rear impact. But, this is uncomfortable for normal driving. Active headrests avoid the conflict and achieve better protection by moving the headrest up against the head upon rear impact. Recently Toyota announced an active headrest design to be used in all future models (somebody posted it somewhere on this site).

By the way, being a short person, I almost always find airplane headrests terribly uncomfortable. They push my head forwards so much that I am constantly having to use my neck muscles just to hold my head up. And airplane trips can be long! Taller people's heads are higher, and they don't suffer in the same way. People like me on the tails of the statistical distribution just aren't catered for!

Stan