These days we have gone too far in the other extreme.
My grandfather needing a blood transfusion in 1990 and was seen as a death sentence because of how little of the blood was tested then in Eastern Europe. It ended up that my father and uncle had to take turns donating blood to try and keep him alive.
When people talk about taking blood from high risk groups and call me a bigot for being absolutely against it I always remember my father fainting three days before my grandfather died because he had given too much blood.
There is, but it does not seem that we learned it. Being a simplistic and tribal species seems to be very deep in our nature, sadly.