I was amused when I read the fourth paragraph of the article where it talks about how a United States immigration officer might ask a person applying for citizenship who is the second in command of the U.S. government. I was amused because there are plenty of people who have lived in the U.S. for their entire lives and they have no idea who the Vice President is; who holds the office.
I think most of these interview questions have little value in telling us whether a person will be an asset to the country. It's great if you know what the flag looks like and you can sing the national anthem, but why does it matter? Unless you plan on getting a job singing before sporting events, I bet there will never be a time when you absolutely need to know the words to the national anthem.