You know the guitar is complicated, and so do I. There are different ways to do everything, and the fact that all the strings are tuned in fourths EXCEPT the interval between the second and third strings makes the instrument truly schizophrenic. But look, if you understood other instruments one percent as much as you understand the guitar, you wouldn’t beat yourself up as much.
El Kabong

Some instruments are too simple. Bagpipes don’t have all the notes on them so you are pretty much relegated to playing folk music idiomatic to the culture where they play bagpipes. (I tried bagpipes once, in Scotland, and I was shoving air into it so hard I almost fainted, and it wouldn’t make a peep. Then for no reason it would ERUPT in sound, which scared me so I stopped blowing, it would close up, and, panting and sweating, I had to start over. Stupid instrument, or should I say, stupid American?)
It’s about right on piano. There is one place to play any given note, and you can play any note. You can play chords. And it’s all visual, like guitar or vibraphone. If you teach jazz combo, the pianists always get it first. The instrument doesn’t get in the way.

With wind instruments there is usually a common way to do most things, so they play a given scale much the same way most of the time. Trombone is the most complicated among the brass and wind instruments that are used to play jazz.

All string instruments have more than one place to play a note, but again, guitar, between having six strings and the tuning glitch, is nuts. If you play in first position there is a pattern to where notes are, but if you play in second position the pattern changes because you moved your hand. There are 12 positions on the neck before everything repeats, so it’s like trying to learn 12 different instruments. Now do you see why guitarists have difficulty reading music? We are trying to do things on a much more complicated instrument than anyone else.

So here is the solution to everything: Whatever it is you are trying to learn, you need to first simplify the instrument. Then you need to learn the thing you want to learn. Then after you have learned the thing, you can go back and complicate the instrument back up again.