Originally Posted by
Rhodabike
I'd guess that shorter distance races are more likely to attract beginners doing their first race ever. Some people are very unprepared for the swim portion and get bad advice ("You don't have to know how to swim well - your wetsuit will let you float through the swim leg!").
Bingo, we have a winner.
And add in those who figure they will suffer but get through it. Figure on a mile swim people actually train and if they do fail they still have something left.
Back when I was swimming competitively 400 yards was the minimum for the warm up to start a workout.
Also for longer distances the race organizers are more apt to anticipate some will have problems. At 400 years one does not and there might not even space for any safety boats.