That one.... yeah, you can tell none of these people had first aid training, since in some cases you really shouldn't be moving one's head or body (which could lead to a more serious injury and a lawsuit - I mean, obviously, if the person is in danger, for example the middle of a road, then I get it, but if not...).
I have theories about why they do it, but haven't checked their validity yet
To be honest, I do get why they do it. I've watched some dramas with VIki with the comment on before and people always get confused between who is and isn't related (they obviously skip parts of the episode or didn't pay enough attention).
Also, for example in Dutch, it would be really weird to call someone big sis or bro, I don't even think you call your big bro / sis that, just their name (I mean, it's also very common for children to call their parents by name instead of mom and dad - which personally I could never do).
So I usually put something in the translation notes for the first time when someone is using those terms instead of their name (and when they use *senior to address someone), but use the name for the person going forward. I've worked with editors who prefer to keep the terms hyung / ge / unni / jie etc in the dramas in Dutch and those who argue against it.