Not a biologist but I did stay at a Holiday Inn Express. It does seem fast in evolutionary terms. Also, I'm not clear on exactly what the evolutionary pressures were on those blacks who left Africa long ago and went to Europe. Why did their skin lose pigmentation so quickly? Presumably, they wore clothing so skin color wasn't critical to successful hunting (like it would be for an animal).
One other thing, there's pretty good history covering 5000 years now. That's a significant fraction of the 30K years mentioned. How much have humans evolved in that time??? Does it compare in any way to rate of change long ago? I don't think so.
The theory is that in order for less and less sunlight available as people moved north to make vitamin D, their skin lost melanin. In the early part of the last century (before vitamin D fortification of milk) an outbreak of rickets (D deficiency disease) occurred in Chicago among African American infants because they did not get enough sun.
As far as modern human evolution goes, the key is the isolation of a population. With all the genetic mixing nowadays, it would be hard for much genetic change over time to only affect certain populations.
We don't know what color the original Africans were. They may have had lighter skin and straighter hair than present day Africans, and got darker while everybody else got lighter.