With the guitar, there are A LOT of tunings. To list a few:

Standard
Drop D
Double Drop D
D Modal
Open C
Open E
Open F
Open G
Open A
Open A2
Open Em
Open Am
Open D
Open Dm
Whole Step Down
Half Step Down
Drop C#
Drop C
Drop B
Drop A
G Model

Yeah a lot! And yeah, you can use a tuner, but you can also tune by ear, which actually usually takes a bit longer.

But do you want to know how to tune by ear? Because it actually is a tiny bit more complicated then it sounds.

Well you gotta know what each string is, first of all. Like EADGBe and you have to know what each string should sound like. What you should also know, if you're trying to tune the A string, for example, you gotta know which note is A on another string (like on the E string for example, A is on the fifth fret) so you can play it and it'll be easier to tune. Did that make any sense? Eh, I don't care.

So tuning isn't really that much of a pain, I just don't really like it when I keep having to tune my guitar to play different songs. I'm really lazy.