Hello Ade,

It has been shown in international test matches and premiership matches statistics that the scoring rate from Penalty Line-outs and scrums are significantly higher then from a "tap" and go penalty forming a maul.

By law a maul includes two attackers including the ball carrier and a player of the defending team. Meaning that a player would have to "risk" losing the ball in a maul from a tap and go penalty. However, if they set up a driving maul from a set piece the likeliness of ball retention and scoring is significantly higher as the ball is protected by more then two players.