Minnesota
Because some African-Americans are light-skinned.
There is race and then there is ethnicity. Her "race" might be a mix of black, white, whatever, but her ethnicity (or culture) might be African American. For instance, there are white Africans. Their race is white, but their ethnicity is African.
It is not difficult for me to understand this because my family is a complete rainbow with half of them having the same skin color as her, some with skin almost the color of black, and those with brown skin like me in the middle (in addition to those with white pale skin). My family identifies with the Hispanic and African American cultures (and when we put aside the fact that our entire Swedish side disowned us, we claim them as well). The Caucasian people still around in my family even identify with our non-white cultures (even those as light as the girl in the photo).
Similarly, there are some Hispanics that many would call African American. For instance my first reviewer labeled me African American without taking into consideration all of my background probably because of my brown skin (my dad’s side wouldn’t have approved of this). Well, check out Latin America and you will see a rainbow of colors. History is important.
I KNOW THIS IS TOO DEEP FOR TER, but skin color does not necessarily equate to race. Plus race is a social construct (meaning it is not REAL).
So, she may be black, but she is just light-skinned. Lastly, if you review some of the research out there, some researchers do not feel skin color is what defines race. What about the nose, hair, etc.?
There are even some providers who pass as white on the TER boards, though they don't identify that way in real life. All they have to do is flat-iron their hair and no one is the wiser.
You just never know.
I hope that helps, but I am sure it is too much for this type of board. I know we are only supposed to talk about sex, f*cking and s*cking, but sorry I have been on an educational kick lately. Back to my latest book on Search Engine Optimization. Yes, I am a part-time nerd in addition to a full-time sex addict. LMAO!
By the way, according to the American Anthropological Association:
•Race is a recent human invention
•Race is about culture, not biology
•Race and racism are embedded in institutions and everyday life.
(And I promise this is the last time I will answer this same question on TER. Now back to thinking about sex. My brain can only handle so much, and it is a Saturday night, so I am about to get laid. YES and Ciao!!)
And what you have to say is interesting but I still just want to know why the reviewer can't remember if he actually had intercourse with her! 
"She gave ok head and I think I got semi-hard. I don't remember if we fucked or not, nor if that was included in the price for a half hour."
Either she "did" him so well that she knocked him out or he was on something strong. Either way, it's too funny. Good catch!
Now, off to get laid...
Xoxo.