This is almost surely a data collection problem. For example, are people tagging the right accounts? For Bandon Dunes or Pebble Beach, is there an account for each course or are people tagging the resort? How do you attribute those differences?
It also, just doesn't pass the smell test. As Tom mentioned, many of the privates have few guests. Bandon has to have 50,000+ times as many visitors as Chicago GC. My best explanation is that a lot of posts that are highlighting "Top 10 Courses in America" are bringing up the count for exclusive courses. As with anything using data, definitions matter.