As much as I think "tort reform" is a right-wing dog-whistle term, medical malpractice law has a lot to do with cases like this. Put simply, if you're insured and there's an incredibly remote chance that a test could show something, most doctors will issue it - it doesn't cost them anything, it doesn't cost you anything, and it protects them if something happens to you in the long run, at which point they can say "well, we tested for it and it was negative, so it's not our fault". From the doctor's point of view, ordering the additional test (or surgical procedure, etc.) has very little downsides and either marginal or significant upsides, depending on what ends up happening.
If you're interested in this, read up on the PSA (Prostate-Specific Antigen) test: it's the main test used to check for prostate cancer in males. You'd think that doctors would issue it to all males of a certain age annually, and up until recently most doctors did that. But there's been an interesting change of thinking in the past few years: someone noticed (and importantly, some insurance companies agreed) that the combination of an increase in the power of drugs/surgical techniques available to treat the disease and a stabilization of the relatively-high false-positive rate in the PSA test (and the dangers of what happens with a false-positive) means that unless someone has a predisposition to prostate cancer, it's often better not to test for it. The net result when the options are getting prostate cancer and taking the treatment vs. getting screened early and undergoing the invasive diagnostics needed to confirm a PSA test at that stage, it's usually a better choice just to get prostate cancer.
Note that this math goes out the window, however, if you have a family predisposition to prostate cancer. In that case, the risk of option #1 goes up (since it's predicated on the relatively low incidence rate of prostate cancer), and the dowsides of option #2 go down (since the probability of a false-positive is much lower).