I hate to say it, but it doesn't have to do much with race, but more of the perception of "status" of the person.
I have been in Sweden few times (I am white), and when people hear me talk, and know that I am visiting from NYC, I get a bit of more friendlier service.
Including getting in a club as a single guy, because I had a california ID, while some Swedish guys were being left outside.
Swedes have a high affinity for America in general, and are extra friendly if they hear you are from the States, and often (with some small talk) you will get preferential treatment.
In NYC you will notice this "differential" treatment according to your status every day. A simple experiment you can run: Go to a good cocktail place/bar with normal t-shirt/jeans clothes, and go to the same place dressed sharp. You will get a lot better and faster service if you are dressed really well (and your perceived status is higher), while if you are dressed like a schlub, you might not even get in the place.
I think it is not just about race, but more of the perceived status of the person. It happens that most countries in Africa have very low GDPs, while most countries in Europe, and north america (US and Canada), have very high GDP. If you are an average person from those countries, your purchasing power is higher, and hence you will be given the preferential treatment.