You do realize that every single unit of blood donated is tested for HIV and other diseases. Right? No of course you didn't. If you did, you wouldn't have made such an insipid thread.
You do realize that humans make errors don't you? How do you know all blood that's donated is tested correctly and no screw ups happen? Somebody doing the testing could get the test tubes mixed up or make some other mistake. Perhaps the HIV infection is early and can't be detected?
Buildings have literally been built on the wrong lots. Numerous instances of that. There are numerous check points to prevent that from happening and yet it does.
https://www.iheart.com/content/2021-08-30-texas-couples-forever-home-accidentally-built-on-wrong-property/Not allowing gays to donate is just one filter to prevent HIV tainted blood getting into the system. Sure some of these gays will lie on the application and say they have not had sex with another man. However having that restriction will deter some gays from donating blood.
People have actually gotten HIV from donations. So mistakes do happen. Don't be naïve / moronic LurkerNoMore.
https://www.japantimes.co.jp/news/2013/11/26/national/blood-of-hiv-infected-man-used-in-transfusions-source/A man in his 60s contracted HIV after receiving blood donated by an infected man that slipped through safety checks by the Japan Red Cross Society, the health ministry and the Red Cross said Tuesday.
It is the first time since 2003 that someone has been found to have been infected with the virus apparently via a blood transfusion.
Health minister Norihisa Taumra confirmed earlier in the day that blood donated by an HIV-positive man in his 40s that slipped through safety checks was used in two transfusions at separate medical institutions. Officials are trying to determine if the other recipient got the virus.
In 2003, there was a similar case of a patient being infected with HIV-tainted blood used in a transfusion, prompting the Red Cross to strengthen its safety checks the following year.
The Red Cross said during a Tuesday meeting of the ministry’s blood program panel that it will change its current safety screening method of examining blood samples jointly in batches of 20 donations to examining every blood sample by next summer.
The ministry said the blood recipient received a transfusion in October as part of treatment for a chronic digestive disease.
The man was found to be HIV-positive during blood screening in November but had also donated blood in February that slipped through the checks and was provided to medical institutions.
It is possible the infected blood slipped through the virus-detection system because HIV levels are low during the early stage of infection.
After the virus was detected in November, the man admitted he had had risky sexual contact shortly before he donated in February, but had lied about this earlier.
The ministry now suspects the man donated blood to discover whether he was infected with HIV.
Taking this into account, the Red Cross will train doctors to better discern who could be at risk of infections when interviewing blood donors.
The man had also given blood in January 2012, but the ministry believes this donation was not tainted because because he was most likely infected either at the end of last year or beginning of this year.
