Yes, a teacher can do much better in the States. I gave up a situation where I was working at two different colleges and earning a wage far superior to what I am making in China. I came here to help. Pure and simple. But I didn't come here to be taken advantage of. If your country makes it clear to me that my help is no longer needed or appreciated, I'll gladly go elsewhere.
You erroneously stated that Chinese teachers are working many more hours. Very rarely the case. Also, they are usually working under a a very generous retirement plan ("the long road"). Furthermore, they don't normally have to pay the prices that we as foreigners have to pay. More importantly though, they are living in a household where there is more than one wage earner and they also know how to make their money stretch in China.
On the other hand, you are correct that the underqualified teachers have nothing to complain about in terms of wages and benefits. In my opinion, they shouldn't be allowed to teach here without first having gained some experience at home. However, before we can balance this problem out, a wage must be offered that will lure the more qualified teachers. Until agents and schools start doing so, there will not be a large pool of qualified applicants to choose from.
Finally, you must take time to realize that many of us here in this forum are not speaking for ourselves. We are merely providing advice to less experienced teachers with the hope that they won't make serious mistakes or misjudgements as they begin teaching abroad.