re: Why don't they execute the read-option in rugby?

Can't hand the ball off forward.

But I think I understand what you're trying to say. One of the first things that is taught to new players is how to draw your Defender before your pass. Making a 2 on 2 into a 1 on 1 or less. Looping after you pass and running switches (outside man cutting behind you) are two other common ways to create 2-on-1's