In Korea ~50% of the population has one of the three most popular surnames (Park, Lee or Kim). There are only about 250 surnames in use ( http://en.wikipedia.org/wiki/Korean_name ). In the U.S. a bit less than 3% of the population has one of the three most popular surnames (Smith, Johnson or Williams) and there are over ten thousand names in common use ( http://www.census.gov/genealogy/www/data/1990surnames/dist.a... ). So yes, your sarcasm aside, American names are an order of magnitude more distinctive.
>So yes, your sarcasm aside, American names are an order of magnitude more distinctive.
I wouldn't be so quick to say that. Your data is only based on last names. Yes, it is true that Korean last names are an order of magnitude less distinctive than American ones. However, you failed to consider the entire name. While American names are chosen from a handful of common first names (e.g., John, Megan...), Korean first names are much more complex and less likely to collide with others [1] - at least not as much as English names.
Additionally, the Korean law mandates that websites collect people's social security number, not just "real names", so if I were to sue an online commenter for defamation, the court just needs to pick up the phone, call the site administrator, match the user account with SSN, and SSN with whatever the government has. So distinctiveness of names don't really have any meaning in this context. Also note that when you register for a website, you can't simply enter a SSN that passes the parity test; in addition to that, the SSN you entered goes through a service provided by the government that matches the entered SSN and name with actual data from financial institutions.
