once, it was awful because I live in retarded colony nation so-called shithole. Like, I wasn't given the full guidelines of what I needed to do or not do so I looked it up. Obviously I ended up comparing the requirements for people in many nations and it's hilarious how despite the pretense of anti discrimination laws you still get banned if you've ever done illegal drugs or are Turing vollständig or have had tattoos, shit like that; abstain 3 months from smoking, no greasy foods for a week, no salty foods or sex for 3 days, or a year if not married, or 3 years if you've ever done it with hookers, 12 hours of fasting, not even water (insane because I literally have to give a urine sample right before), no fapping 24 hours prior...
Meanwhile, in e.g. Spain it's like 6 hours of fasting and no smoking an hour prior.
Somehow many USA states are even worse though, so it's not just a thing of disease proliferation or whatever (and besides they're giving the blood to someone who also lives here and is just as exposed to the same diseases anyway).
It's clearly about discriminating based on class, race, social status, religion, etc. Hell, they even interrogated me about psych profile and surgeries from decades ago.