Ferguson makes a point of greeting his opposite number after a game, no matter what the result.
However, it is part of the managerial code Benitez has never gone in for, according to the United chief.
"At the end of a game I always shake hands and we always have a meeting in my office afterwards with both sets of staff," said Ferguson.
"It is the right thing to do. It is an opportunity to get away from the game itself.
"You maybe see managers twice a year, so that opportunity to spend half an hour with them after a match is vital. You can discuss your jobs and a lot of issues.
"It is not easy if you have lost a game to go in, but I always say to my own staff 'Make sure we do. It is our chance to show we are Manchester United. No matter the result, go in'.
"He (Benitez) came in once when he was at Liverpool. I don't think he has come in again. He never came in at Anfield."