T/Arg. has nothing in common ????????
etc.
Both Amer . and Intern. style have their roots inextricably tied to T/Arg.
If you have danced ( by your statement, apparently not ) all 3 , you would readily see that there are numerous variations closely related, and some identical .
What varies primarily is the style.. the music has now crossed over from the T/Arg.genre into Intern. style comps and demos .
( even a gancho was being used at one point by a top pro. )
I do teach and dance all 3 . As to no structure, there is a step list with a breakdown of the levels that has been in print for a number of yrs ( by Paul Bottomer, former world champ. )
The UKA provides exams at all levels .
As to structure... you are correct to a point.. like salsa, its intent is more freeform, but in reality, like all dance, it has a basic foundation.
if there were no common ground, no one would be able to lead and or follow .
And by the way....... why do people seem to think, that every dance the comp. world gets its hands on, its an improvement ?... in most cases, as I have previously stated.. it eventually becomes a caricature of the original form ( with few exceptions ) .
And by the way.. I,m not saying that you, or anyone, should embrace the concept.. only respect it .