Making a bit on the side, isn't that perfectly normal?
If you really only take home two to three thousand yuan after deducting social security and housing fund, it's not enough to support a family. Who would still want to be a doctor?
At least before there were explicit policies against it, this is how everyone operated.
Prescribing medication, using consumables, and taking kickbacks also constitute a sizable income.
After getting promoted to attending physician and gaining some fame, one could make extra money by consulting at other hospitals a few times a month or collaborating with some smaller clinics. That, plus a regular salary, could make life quite comfortable.
Apart from these gray income-generating methods, doctors also had many other ways to increase earnings.
It varies from person to person.
In any case, as long as it's not blatantly exploiting patients or fleecing their families, it's acceptable.