> That’s when I realized that there is probably some actuary in Chicago or somewhere whose excel sheet says the risk of the wrong transfusion goes down by 0.02% if you draw blood before labor.

1) For what it's worth, you don't know for sure why they wanted to draw blood again. There might have been some other reason, that they possibly didn't do a good job at explaining to you. I guess there's a disconnect between doctors who might order tests, and the people who actually draw blood, leading to bad communication all-around.

2) Like with most people, I think the medical profession as a whole is bad at sensible risk-management. I'm not a doctor, but I think they get a lot of training on what to do to avoid lawsuits, and this guides a lot of their thinking more-so than common-sense and sensible care. This probably guides a lot of unnecessary tests where a doctor might think something like "Yeah they don't really need to do that test again, but their insurance will pay for it, and I can eliminate the possibility of being sued if I play things by the book."