How much are they paying?
From what they tell me, they start them at a below market rate for the following reasons:
Many need on-the-job training
They need to see if the worker will be making money and saving time for them - can they be trusted to do the job right (reducing oversight, tear-out & redos, etc.)
Can they demonstrate reliability (showing up, doing a decent day’s work, treating customers & the property well, reputation, phone use, etc.)
Once they find a good worker, they treat them like gold.