Some whites are white trash. I don't think that's the same thing as the OP is talking about tough..
How would it not be the same? Its a white person calling another white person trash and specifying race. If thats not the same thing then the OP is more out of whack than I thought.
You don't call just any white person white trash. You call white trash, white trash. Black people that call each other nigga do it to replace their names. "White trash" is a way to describe a lifestyle. Nigga isn't a lifestyle.
"White trash" is a way of relegating a white person down to the level that you think they should be, just like the word "racist", "fascist" etc.
White "racists" are always called "white trash" and "redneck", regardless of their actual lifestyle and social standing.
The closest thing to "white trash" is the word "ghetto trash", and that term is almost always regarded as a racial slur, despite being much less racial from the offset than "white trash"
"White trash" is only acceptable because society is systemically anti-white.