First, $28K in developing countries >>>> $28K in the United States.
I'd only work for that little if I never had call, weekends/nights, and was working 2 days/week max. Probably not even then.
Second, it's basic economic incentive. The best and brightest will go where there's incentive to go. Right now there is a lot of incentive to become a (good) doctor, which is why this country has the best doctors in the world. Imagine what would happen to education in this country if teacher salaries were suddenly $100K/year.
These protesters, like the Tea Party on the other side of the spectrum, are very idealistic and inspiring to many. But both sides' ideas are generally nonsensical and not grounded in reality. We need more people who think with their brains and not with their hearts. At least in politics.