In League it works because there's fewer players who train at long kicks for touch compared to a Union team. In Union, you have the Scrum Half, Fly Half, Both Wings, Full Back, and often one of the centres who will be kicking at distance for touch. In League you've a couple of players who are used to kicking: whoever takes the conversions/kick-offs/dropouts and the player who normally plays dummy half on the last play of a set of 6, when you'll usually see either a crossfield kick or a long clearance.