For the reason I've already stated. It's directly related to your ability to judge of the case soundly. If you aren't black, you just don't know what it's like to get that kind of threat. It's recent enough in history to be taken seriously. The difference is this: most people make death threats and don't mean them. And probably, you know that if someone has had a couple beers, gets mad, and tells you he's going to kill you, you'll know he's probably not serious. But if that person happens to be, say, Whitey Bulger, that's serious. A threat of lynching carries that level of fear for a black person...and unless you're black (or at least some minority with similar experience), you flat don't understand that point.
1. White lynchings account for a small number of all lynchings in the U.S. In short, white people haven't had to face engrained racism and discrimination in this country.
2. When white people were lynched, they were most often lynched for committing some crime. Black people were lynched usually for just being black. Threatening a black person with lynching is like threatening a Jew with a gas chamber or an Indian with the 7th cavalry. It's downright low.
