First of all, not everyone who works remotely works from home. Self-employed people can have offices (and I don't mean home offices) or studios.
Here's an economics lesson for you.
Let's say I have $100 to spend on shoes. I decide that I am going to save money and only spend $10.
Store A and B both sell shoes for $10. Store A sells good shoes that fall apart quickly. Store B sells shoes that are of excellent quality, despite their low prices.
If I buy shoes from Store A and they fall apart, I don't care, because they only cost me $10. I can always buy another pair. In fact, considering that my time has value, it's cheaper for me to buy another pair than to go down to the store and complain or to complain to some consumer organization.
If I buy shoes from Store B, I'm very satisfied. The shoes are great, they're comfortable, and they last a long time without needing repair. For me, everyting is great. But the owner of Store B is going to be looking at what competitors are doing. When they realise they could be selling shoes of the same high quality for 10 times as much and still charging less than competitors, they are going to raise their prices. Nobody is going to sell for less than they have to.
Now, lets say I decide that I'm not going to be cheap; I'm going to spend the full $100.
Store C sells $100 shoes of great quality. Store D sells $100 shoes that are of terrible quality.
I shop at Store C. I'm satisfied with my purchase, the owner is happy because they've made a decent profit. Everything is fine.
But suppose I shop at Store D, where the shoes are terrible, but I don't know this. The owner has made an incredibe profit because he has probably invested next to nothing in materials and labor. On the other hand, when the shoes fall apart after a few days, I am furious. Because I have spent a large sum of money, I have the incentive to do something about the way I was defrauded. I tell all my friends never to shop there. I post on every review sight I can think of. I post on Twitter. I report the company to the Better Business Bureau. Every other person (and there are many) who has had a bad experience with this store does the same thing. Eventually, maybe someone's Tweet gets picked up by someone who works at a local news station and the store is investigated on the news.
Now, getting back to oDesk. Yes, there are freelancers who are very good and are woefully undercharging. If they they research other freelancer's profiles, they will realise they can raise their rates.
There are also freelancers who charge a lot and are awful. But they will either get bad feedback or, if they want to avoid this, refund their earnings. But it is harder to refund $1000 for a job than to refund $25 for a job. And even if bad feedback doesn't go on your public profile, oDesk still has it on record and can suspend your account.
Do you honestly think that someone like Bojana would be able to charge the rates she does, have had the number of jobs she's had and maintained a close to perfect feedback rating if her work was no good? Get real.