This seems to use private education as a benchmark for the entire argument. From quit rates, to pay, to conditions, and beyond, but ignores the obvious which is that private pay and private conditions are largely pinned to be just above public salaries and conditions (meaning private education cannot be used as a benchmark for when someone is under-paid, over-qualified, or has too high of a quit rate because they are…
I think your confusion stems from the fact that society does not decide salaries. In the private sector, salaries are based on how much one's involvement in some endeavor causes that endeavor to generate more revenue (or how much you can convince someone your involvement generates more revenue), combined with how easy it would be to find someone willing to do the same job with the same impact at a lower rate. If the value add is high and there is no one able or willing to do what you do for cheaper, you will have a high salary. If you add little value, and no one is willing to do what you do, you will be fired and likely not replaced -- they'll do without. If you add lots of value, but someone else is willing to do your job for less, you will be kept around if you accept a lower salary. If you add little value and someone else is willing to do your work, they will be hired for a lower salary. This isn't rocket science.