"All over Asia, all these 60 year old American, Australian and British men always seem to have young, 20 year old girlfriends. I'm thinking, the closest those people
will ever get to women that young back at home is at a brothel. "
No country is free from women who will seek out men who can give them money or whatever else they might want. I take it you've never heard the term "trophy wife," and the complaints of middle-aged (or not even that old) American women who've been divorced by their same-aged husband so he can be with someone younger and prettier? And there are people like Anna Nicole Smith, former Playboy model, who at 27 married an 89-year-old multimillionaire who had had married twice before she was even born (and when he died, his heirs claimed in court that he couldn't have been in full possession of his senses when he married.) Maybe she didn't marry for money, but the idea is common enough that many assumed she did.
I don't approve of that behavior either, but you can't say it's only characteristic of people outside richer countries.