Because racial identity is about more than skin tone. Because it's made explicit that people can't tell Shadow's race by looking at him. And because the coffee-color thing is widely mocked in writing about this issue: see here and here just for starters.)

And -- people on this thread ARE actually discussing textual details in the book (the conversation with the guard, the 'sickle-cell' reference) and having different interpretations of what they mean. This is the opposite of "not paying attention."