The article says these tests can be "at a cost that is as much as 80 percent less than going through a doctor", what can explain that kind of discrepancy besides rampant corruption in the "official" medical lab work market?
The difference is that one is paid for by a health insurance company, and the other is paid for out of pocket by the consumer. The second group is much more price sensitive.
Cost: I don't know why the difference is so large; that seems like a serious problem. For what it's worth, I don't make a single extra penny on lab tests. As far as I know, most doctors don't (except maybe the pathologist who runs the lab). We just order what's indicated.
Would I say that the average person should be able to get a cholesterol test if they want it? From a rights/freedom standpoint, absolutely. Would I worry that they would misinterpret it without guidance? From a medical standpoint, absolutely.