The off trail lady who died is an unfortunate example of unpreparedness and lack of knowledge. She apparently had difficulty earlier on the trip in orienting herself to her surroundings. I doubt there is anything particularly difficult about the AT compared to other areas.

Basically, you need a good topo map, along with the skill and experience to use it. If you get messed up, sit down and carefully work out a strategy; don't just sit passively and wait for someone to ome and rescue you.

GPS is a great tool, don't get me wrong. As an archaeologist, it is great for definitively locating sites and items of interest. But it is not infallible or perfect.

I once located an arch site in a rock shelter on the side of a prominent canyon within a bend in the canyon, clearly indicated on my topo map. I took a GPS reading. When I plotted the numbers, the location was several hundred feet to the west, in the middle of the stream bed. Cliffs and tall buildings, etc. can deflect GPS signals and throw locations off, sometimes significantly for some purposes.

GPS technology really shines when you are in relatively flat, featureless terrain where signals are not deflected and you don't have visible landmarks for orientation.
Geezer in Chief