Now, your point for the rising number of scam ESL writers making it difficult for legit ESL writers to find work.
I think we should bring the discussion back to the original question: Are native english speakers really better at writing?
The question is simple, but the answer is complex. For example, most of my native English speaking academic peers (PhD scientists at the top research institutions) are horrible at writing. One of my dear friends is the daughter of two professors and hails from Oxford University. She has the greatest trouble getting published despite being an excellent scientist. Her writing just sucks - I know because I am her personal editor. Then there is a colleague from Switzerland who speaks several languages fluently with over 100 published works in all sorts of venues. I feel like a moron whenever he glances in my general direction. Technically, his English is much better than mine will ever become, however, his writing reads in a very mechanical way. Consequently, he often asks us native English speakers to adjust his writing for things as simple as newsletters. I'm not a cunning linguist, but I think that this is very suggestive on how much influence culture can have on how we construct our sentences.
I also work as a contract editor where my job is to take ESL manuscripts and make them sound like they are written by someone from either the U.S. or the U.K. This, combined with my professional experience has given me the ability to spot the ESL writer almost immediately.
Although a good bit of this industry handles graduate level work, we're mostly talking about undergrad papers in this forum. Speaking as a lecturer who has received essays from students who obviously had no hand in the writing, an ESL writer would have likely served them better in terms of economics and by throwing me off their trail. Even though I cannot prove that many students are cheating, I will **** with them in variety of ways that satifies my level of sadism. Its much more effective, and easier on me, to make life difficult for a cheating student than it is to run them up in front of the dean. I truly believe that a good life is to understand that you never know when you are messing with the wrong person.
If you are a Chinese student who hands in a paper that sounds like it was written by a white guy from the New England, then your professor will likely be zeroing in on your little scam. You won't get caught, but you also won't get the benefit of having your grade lifted out of the failing zone - this is something that nearly all lecturers/professors do for lots of reasons that I do not want to get into. And, if you get a professor like me (there are a lot of us), we will ride you like a workhorse because our intellect was insulted by your blatant display.
Likewise, if you are Johnny Whitebread from suburban Sameness, U.S.A., then you probably do not want an ESL writer. The influence from MTV reality shows and the extreme desire to be famous simply will not come through. However, another twisty caveat is that most professors do not really read your essay. We skim through looking for gradable points and obvious errors. We do not have time to digest yet another ten page paper about global warming, hot and sweaty polar bears, and how Al Gore could have saved the world if he wasn't a fat slob. And we all sit around the table at the local pub and lament the fact that we do this. So yeah, an ESL writer might suffice here, but then again, maybe not.
Then we get to the upper level classes at a teaching school. You know, the one's where the professors are there to mostly teach. They will likely read your paper and will likely flip a ******* lid if they see you using the word 'whilst' instead of 'while' or 'amongst' versus 'among'. Catching this will just irritate them even more such that they will go back and re-read your crappy paper. Yep, they have that much time and they love having that little bit of insignificant power. It makes them gnash their teeth and pound their chests. Some of the ESL writers on this board are so verbose and use so many 25 cent words - nearly zero students in the U.S., even at the Ivy Leagues, speak or write this way. I'm looking at you Antarch!
Or maybe you are that student who was just a jerk the whole semester. I will zero in on your paper because I know for a fact that you are going to pull a fast one. I will **** you so hard with my red pen that it will really look like your a-hole was bleeding all over the paper. And your poor class mates. ****, man. Because I reamed your ream so hard, I now must grade your classmates with greater scrutiny so I don't get in trouble for singling you out. I know that you'll cry foul, and you'll be right, but can't prove it just as I can't prove that you hired some ESL writer from wherever. And it will all be worth it because those students who are the biggest jerks are the same who usually suck up most of my time. Payback *******!
That felt good to finally get off my chest.
So yeah, lots of caveats and pitfalls. The ESL versus native English writer debate, as it stands here, really falls short. As Meokahn suggests, there's a whole lot of gray territory. The original question of who is better is actually one-dimensional and doesn't address the reality. As far as I can tell, there seems to be room for everybody to have a slice of the pie.
There is another aspect that few of the ESL'ers here seem to get. Most of the ESL ghostwriters are scammers. Period. End of discussion. Don't fight it. I'm truly sorry, but this is your burden to overcome. Getting all worked up about this fact will not serve you in the long run. You absolutely must set yourself apart from the others because, like it or not, American's are an insular bunch and generally don't really see the difference between a Nigerian and a Kenyan. I know it is a sad indictment of my people, but this is the reality. You are not doing yourself any favors by trying to elevate the general population ESL writers.
I await the insults, slander, name calling, and general twisting of my words.