I wanted to comment on this also. Didn't they walk from the apartment and haven't people said thats like a 15 minute walk. I care about chivalry and I try to do the right thing I always open the door, hold the door etc. etc. but I could easily see myself if i walked with a friend the better part of a mile and our paths split at a point where her car was 50 yards away i could easily see myself feeling like thats good enough. It's not probably the best thing to do but I think it could easily be done by some one who is not a total jerk.
I'm not as young as these kids but i think i'm not as "experienced"
as some of you, and I just want to say things are not as obvious as they once were. In the past it was easy to be chivalrous because it was somewhat expected and it was almost always positively received. That is not necessarily the case anymore. With some women it is but with others they don't like it (beyond the basics like holding the door) from someone they don't know that well. I think it can be perceived as invasive or too forward, and if they politely decline if you insist that would instantly get you labeled as creepy. A lot of times these days "let me walk you to your car" is interpreted as let me get a chance to chat you up alone at the end of the night. If the young lady isn't interested in you and you are very casual friends I think a lot of the times they would decline an offer. CM seem to be pretty independant minded so I could easily see that.
Just be clear if you are with a young woman that is interested in you, you are on a date, or you're a couple then chivalrous things are still wanted an appreciated. But otherwise not so much (to the point it can be perceived as creepy or controlling).
In summary walking all the way to her car and waiting to see she got in and the car started probably is what he should have done BUT I don't think him not doing that is a huge red flag or anything.