Far be it from me to try to convince you to wear a lid when you've already convinced yourself otherwise.  It's not my business but I hope it works for you and you never need it.  So far as donating goes, you're absolutely right... for now.  But, with BSE/mad-cow now having been discovered in the US and not from imported beef, that could change in the future.  The reason they do that is to lessen the possibility of someone who has unknowingly contracted Creutzfeldt-Jakob disease from donating.  It may still be a while though since only one's been found in the US and Britain has reduced theirs systematically since the early 90's to something shy of 100 cases of BSE per week now.