I think most people in this country might well take "y'all" as a lot more in-your-face than "you". And be taken aback to find "you" seen as confrontational on a visit to the States.

It all gets very confusing. I think the best rule in life is always to start from the assumption that strangers are not trying to put you down by their unfamiliar ways of talking. If they are it will become clear soon enough.
...............
'ya' in slovenly argot, e. g. in "What ya want?," "Where ya goin'?" (Q up the thread)

I think that is an example of "eye dialect", a term I found in an enjoyable book Accomodating Brocolli in the Cemetary:

"Eye dialect looks like dialect but sounds like standard spoken English when read aloud...It often suggests that the speaker is illiterate or ill-educated although they are actually speaking in the same way as everyone else"