When you are working in a lab, you are using HIV that is at really high concentrations, not physiological concentrations. This is because HIV, as you said, is not very infectious and as a scientist you want to be able to infect things to study pathogenesis. If the blood that you touch is infected with HIV made in the lab, then you should be worried. If you physically contact blood from an HIV+ donor, then most likely they are on HAART, and the concentrations are undetectable. You can be less worried in that instance, however everyone is going to take full precaution and get the exposure treatment.
It is required by the BUA that you take the appropriate precautions when dealing with blood and that you respond accordingly to the level of infectious threat, which if you work with HIV you'll know.
I know people have personally pricked themselves and have not gotten HIV. HIV research is not that scary compared to other infectious diseases.
The bushmeat theory is the most believed story of the zoonosis of HIV.
Also, if you cut yourself and believe that there is a chance that it was infected with HIV... why would you not get PEP? You can take your chances if you want, but I'll get PEP anyday in that situation.
The reason why this thread is getting so much attention is not because of the subject, it's because you are a gunner and no one likes your tone. You might have done a little bit a research on HIV and you feel like you know something, but SDN isn't the general population. Realize that on these forums there are actually people that have done the same, some of whom actually know more than you do.