Argentine Tango music is completely different from other forms of dance music.
It may be different but when it comes to degree of understanding music, the salsa music is more difficult. So if your point is about difficulty of music and dancing to it, tango is a difficult dance to less difficult music. Salsa is simpler dance to more difficult music.
so you can't count it like other dances
Count what? You can dance without counting.
You have to become familiar with a lot of orquestras.
I can’t speak for you and the others. For myself I don’t agree. I am still not familiar with orchestras. I might be familiar with some music but if you ask me which orchestra it belongs or what is the name of the tango song, I am likely to draw black. Because I didn’t put any effort into it. I know it is a tradition among tango dancers to learn their orchestra etc. However I haven’t found correlation between musical dancers and encyclopedic knowledge of orchestra. It may be necessary to DJ but I don’t DJ.
When we dance and we want to be musical, we wish to express the emotion of the music as we perceive it. The emotion can relate to rhythm, melody, etc.
We all learn and pick up things differently. Musicality as understood by a musician is different than musicality that a dancer needs to express. Because dancer has to use movement and coordinate it with a partner to express musicality. That requires accommodating to the partner. Otherwise I can go solo dancing to EDM at a night club very musically. Or I can also dance alone to Tango music and express my musicality. But tango that we enjoy is a partner dance.
But first, you have to understand music. I'm fortunate because I took 3 years of music theory and 3 years of piano lessons in high school where I learned the difference between notes and beats.
It is interesting for sake of curiosity. I have tried to learn about music theory. About beats, notes, scales, tonality, harmony, polyrhythm etc on my own. I doubt I grasped more than 10% to 20% of it because I did it in my free time. Not as a rigorous study.
I don’t know what you mean by understanding music. But you can teach beginner dancers how to dance to the music without having to understand musical structure. You can focus on a few things in music that standout louder like accents, etc.
I have seen it done in beginner classes and it does work.
So no, if you are a dancer you don’t need to understand music. You need to understand movement. You need to understand mapping movement to what you hear. You need to understand movement when there is another person right infront of you.
(They aren't the same.) Leaders have to fit figures to the music, like jigsaw puzzle pieces smoothly entered into the puzzle.
There is definite way in which jigsaw puzzle pieces fit. There are infinite ways to fit a movement to a passage of music. Whether you choreograph is dynamically on the spot (improvisation) or you program it before, you are still trying to fit a sequence of movements (figures) to the music.
Let’s leave apart those who don’t try and are only executing movements irrespective of the music. Among those are many who understand music. But as I said there is no correlation when it comes to dancing.