Two-tier Facebook - Friends and Family

I don’t get why Facebook don’t implement a two-tier friends system. You could call it friends and family or even family and colleagues or whatever. But having a way to restrict posts to a closer circle of friends would reduce the dilemma1 that the average person faces many times in their Facebook lives:

Do I accept a friend request from my mum/dad/boss/colleague/teacher/whatever and risk getting in trouble for something I or my friends post, or do I ignore their friend request and risk the wrath incurred by doing so?

  1. Ignoring the other less critical dilemmas in life like “where’s my next meal coming from?”