The name of the game is volume. The problem is that you are so exhausted and overwhelmed that you don't have the time to check that you are being paid for all of the work you have completed and for the correct pay. It is important to check all payments that you receive because you are often shorted.
I don't think anyone will ever say which companies are good to work for since they live with the fear that those companies will find someone to complete the work for less. It happens all of the time. The less that the laborers are paid, the more that is left to line other people's pockets.
Once again, this is an extremely tough business.