I have a Sikh temple in my town, so I know the difference. If you live in a large metro area like Atlanta, it's likely that you would also have been exposed to this rather small Indian sect.
Take that 75 miles out of the big city and that isn't the case, and when somebody's never seen a Sikh before, he's just another foreigner with a rag on his head. Believe me, there are a lot of people who don't know the difference.
Pity, since Sikhs are very pro-USA.
Well, of course they might be mistaken. Hindu Indians are mistaken for Muslims. It’s just that there is as much evidence, at this point in time, that the shooter knew what he was doing as there is that he was acting in total ignorance about Sikhs. Temples do not look like Mosques (although I don’t know what the one in Wisconsin looks like)—and Muslims don’t “worship” on Sunday.