Why Do the Best Bowlers Break Off Their Deliveries more than I do?

If you watch the world’s best lawn bowlers on Youtube it is not  unusual to see one of them break-off his delivery and then restart his entire delivery routine. Usually the commentator proposes that some movement either in the crowd or by a photographer has broken the bowler’s concentration. My question is this: Why don’t ordinary bowlers do this to the same extent?

 I think we ought to but we haven’t been taught to- and we haven’t practiced to do so. I am certainly very familiar with the experience of letting a bowl go and realizing immediately that I had lost my concentration part way into the swing. The problem is that I have not trained myself to break it off. I just continue an already doomed delivery hoping beyond hope that some bump in the green or unplanned wick will correct my wayward bowl.