Everybody's ear has to be trained, somehow. Sheet music is a less common way of doing it, but hey, whatever works.

I got my ear trained listening to music and singing along with it as a child. My family encouraged singing, but not off-key singing.  Perfect pitch is basically a matter of memory, and so is just ordinary good pitch. I don't have have "perfect pitch" (i.e. a very good recognition of absolute pitch), but I've got pretty good relative pitch, enough to stay in tune when singing a song. I was in band in my younger years, so I got exposed to lots and lots of scales (on trumpet, and later, French Horn), so I was very used to what a major scale sounded like.

So for me, finding the notes by ear was easy, and using tapes would been a bad idea. But for somebody who couldn't tell by ear when they were on or off, I can see why they'd be a necessity. It's where you end up that matters, not the path you take to get there.