Why not all countries are presented in CultureInfo.GetCultures()?

I am using this standard code for populating list of countries:

static void Main(string[] args)
{
    List cultureList = new List();

    CultureInfo[] cultures = CultureInfo.GetCultures(CultureTypes.AllCultures & ~CultureTypes.NeutralCultures);

    foreach (CultureInfo culture in cultures)
    {
        try
        {
            RegionInfo region = new RegionInfo(culture.LCID);

            if (!(cultureList.Contains(region.EnglishName)))
            {
                cultureList.Add(region.EnglishName);
                Console.WriteLine(region.EnglishName);
            }
        }
        catch (ArgumentException ex) 
        {
            // just ignore this
            continue;
        }
    }
}

I saw that some countries are missed. Just wondered what's the reason of such situation?