This is a bit wrong for Thailand as it doesn't mention nicknames. Or rules for using the given name vs. nicknames. Unless in very formal context it's normal to use nicknames not given names. In day to day life nicknames are by far more commonly used than given names.
Family names are almost never used expect in legal documents or formal setting. It's common for people who have been friends for years to not know each other's family names as they are so rarely used in day to day life.
It's also common also for friends/coworkers to not know each other's given names -- though less so than family names. Especially as you would never call someone you're friends with by their given name as it would be a bit rude. Usually in offices (unless very old fashioned) or with friends and family you'd use nicknames exclusively.
Family names are almost never used expect in legal documents or formal setting. It's common for people who have been friends for years to not know each other's family names as they are so rarely used in day to day life.
It's also common also for friends/coworkers to not know each other's given names -- though less so than family names. Especially as you would never call someone you're friends with by their given name as it would be a bit rude. Usually in offices (unless very old fashioned) or with friends and family you'd use nicknames exclusively.