Beside 1974, why bjorn borg never played in Australian Open?

Question

wiki states that borg would played in AO if and only if he won the first three grand slam (back then, AO was the end of season slam)... beside this, do you happen to know any other reason(s)?

Answer 1

The Australian wasn't always a popular grand slam, and was hard to get to.  Travel to this tournament was more difficult at the time.  

In addition to this, players that played in his era took more time off during the December/January months and weren't required (as they are now) to play tournaments or get fined.  It was (probably) vacation time for him.

Answer 2

A lot of players didn't play at AO because it was played around and on Christmas.