There are various things we could do. As individuals, you could buy brands which have signed up to some sort of agreement for better treatment of workers - in the UK we have Fair Trade (the main focus is agriculture, but they do seem to do clothes as well), and also the more mainstream Ethical Trading Initiative, which some major high street shops have signed up for. As governments, I personally see no reason why we shouldn't have at least some basic worker rights built into international trade deals. It's difficult or impossible to see what things are like on the ground, but at least we could make the existence of national laws mandatory.
[1] http://www.macleans.ca/economy/business/what-does-that-14-sh...
Another thing you could do is specifically look for clothing / articles made in the US or wherever you yourself live. It'll probably be more expensive (both due to higher wages and because "Proudly made in the US" or similar phrases increase the price), but then that's kinda what you're implying should happen.
Anyway "Made in the US" isn't a guarantee for better treatment of workers, iirc there's not much of a minimum wage anymore. People working in the Amazon warehouses are probably the closest thing to the Western sweatshop (and there's a few articles about that around).
[0] http://www.numbeo.com/cost-of-living/compare_cities.jsp?coun...
Local food types (rice, noodles, veg, SE Asian fruits) are ridiculously cheap in Cambodia, though could still very well be expensive in comparison to the wages..
edit: reading further, I'm not sure they've sourced those figures well at all, they don't ring true. 0.43€ for a bottle of water? Come on, that's nowhere near the local price unless you're buying it at your western hotel
What's the price for 1kg of rice there?
We can use tools like Aether (http://www.getaether.net) to give power to voices that may be hushed, find known unknowns in terms of pain.
As for what you can do, you can sew your own clothes.
All freedom is compound interest. Seriously.