Because the people in the shadows represent "white trash" (drinking/smoking/ratty clothes/bad haircuts/sitting on the ground). For those who don't know American slang, "white trash" is a slang term and you can't interchange the word white with other colors because it wouldn't make sense.
Unite-y t1_iqr922n wrote
Reply to comment by [deleted] in "Dirty White Trash (With Gulls), Tim Noble and Sue Webster, trash sculpture, 1997 by cryptowallet77
Because the people in the shadows represent "white trash" (drinking/smoking/ratty clothes/bad haircuts/sitting on the ground). For those who don't know American slang, "white trash" is a slang term and you can't interchange the word white with other colors because it wouldn't make sense.