Back when I was a beginner (not that I've progressed all that far in the intervening years), we didn't have electronic tuners, so I had to learn to tune the guitar either to a tone, or just to my best guess, if a tuning fork or pitch pipe or other instrument was not available.

I learned to tune my guitar using harmonics, which I find much easier to hear. I tuned the guitar to itself using whatever tone or guess was available. It's pretty easy to learn and to do. Now I use a tuner because it is MUCH quicker and more accurate, but I ALWAYS check the harmonics just to verify and tweak as necessary. Lately I have found that the reading for the low E on my electronic tuner (otherwise fine) is inaccurate. For the guitar to be in tune with itself -- or anyone else, for that matter -- the tuner needs to read a tick or two flat. I could get a new tuner, I suppose, but why bother? I know how to compensate for it.

I'm not a guitar teacher (and thank the Lord I'm not, sir!), but if I were I would try to get students to learn how to tune a guitar to itself at some point in the course of their lessons. If they're resistant, fine, it can wait. But they need to learn it eventually. Ever heard of a dead battery?

My 2 cents' worth.

Cheers, Nancy