Very interesting. Thanks for sharing.
Ph.D. Programs give tuition breaks and living stipends, but usually they are limited to 4 or 5 years. If candidates need more time to complete their work, they may have to pay themselves. Article mentioned about students with families. Living stipends don't cover cost of living especially for students with families.
Although it may be very surprising, $30,000 debt for Ph.D. is not the same as $30,000 for a person with B.S. Degree. Hopefully having Ph.D. helps them to pay it off much quicker.
If you learn to do things that you need to do - then someday - you can do things that you want to do.