I think it is normal that we demand more from the doctors claiming to cure us from diseases but we shouldn't be asking them to be gods. They have certain protections against errors in blood transfusions but there are so many that it is possible that an error could happen in the process, we can't condemn them for it.
Blood that is donated is tested for disease before it is donated to other individuals. In addition, medical equipment used to give blood transfusions in doctor's offices and hospitals are sterilized to prevent the spread of disease. As long as blood continues to be tested and there are medical standards in place that are followed for making sure equipment is clean, this should protect recipients of blood transfusions.
Blood recipients are given blood that has gone through testing. Screening of the blood donors is done prior to donation. With the current medications for HIV, people have less worry that HIV will be the life-threatening condition it once was. I feel the current tests are adequate for recipients to receive blood transfusions without the worry of contracting HIV.
Blood banks should be screening and reviewing medical histories as much as possible to protect transfusion recipients from HIV. Blood to be transfused should be screened more than once to make sure it's not carrying HIV or hepatitis. If there are ways to do more screening without damaging the blood, then blood banks and/or hospitals should do more.