It appears to me that there MAY BE

From your post, I gather that you are either QA or QA/recruiting (and maybe hourly?).  I agree that there are some inflated resumes floating around and many MTs do not put out quality work.  Neither of these issues is exclusive to American MTs, though.  I also agree that many MTs quit a job quickly - I'm guilty of this, as well.  There may be a problem with the platform, the interface, the Internet connection, the sound quality, discrepancies in the schedule agreed upon compared to days/hours actually worked, promised percentage of ESL, ability to utilize templates or playouts, workflow, and pay.  These are all issues that can't be foreseen until you actually go to work for a company.  Experienced MTs discuss as many issues as possible with the recruiter prior to hire and hope that the recruiter is honest/informed enough to provide the information necessary, but often that is not the case.  I'm patient with technical problems, as I know they'll be resolved eventually.  But, when you encounter ongoing roadblocks to making a decent living and voicing your concerns to your supervisor/their supervisor/the recruiter gets you nowhere, it's time to move on.  In my opinion, at that point the company has voided the contract, not me.  Your recruiter friend who generally hires twice as many MTs as she needs and ends up holding onto a fourth of them - she's either misstating the conditions of the job or overhiring and starving out the ones who can't afford to sit and wait for something to show up in their queue.  Either way, the MT is the one who loses out.