I saw this movie over 20 years ago I think, it was rural south or rural Texas.
Poor girl lives on the outskirts of town, she is very backwards, men come out and pick her up and take advantage of her (maybe she is being prostituted?)
Younger guy hears about her and goes out there, but he is kinder to her than the others. He buys her a Coke and she looks at it, visibly touched, because no one every bought her anything before. Also, the girl had been bleaching her hair and it looked harsh or damaged, so the young guy asked another girl with dyed hair why hers looked nicer than the 1st girls and she told him she bought some purple pill or tablet that stopped the bleaching process. He gave the girl one of those tablets and she was again very touched at his thoughtfulness. I think he picked her up in a pickup truck.