That's because there are 18 different ways to do it, and different pieces of software use different keys/formats. I can properly set up ssh, but not because it makes any sense.

Similarly I can use git, despite it's best efforts to be inscrutable.

I get that to some degree, and something like PuTTY makes it really unecessarily complicated.

But really, I find that people have trouble running ssh-keygen and then finding the key and sending me the correct one (they'll often send the private key, or more likely they'll send me both "just use the one you need".)

Oddly, to me, the full PuTTY suite is way easier to use then all the ssh stuff on Linux. PuTTYgen/Pageant makes ssh private keys just work, PuTTYgen also has the handy "open a private key, here's your public key for it" text box, that makes everything dirt obvious (of course you can export the public key as well.) And the other major SSH-based software I use (WinSCP) integrates with Pageant as well. I know all this stuff would be equally simple with Linux, but on Linux, there seems to be "use a single key" thing, whereas I prefer to have multiple keys for personal and work use, which Pageant makes trivial.

Not just students - I experience this in the workplace too, and it just boggles my mind. We hired a recent grad, and after about 10 days of watching him type a password into a terminal ~20 times a day I casually mention how he can use ssh keys. His response? No, I'm not interested in that.