People that crashed and totalled their bikes....Why are there always so many DNS? Are those people who registered but didn't show? Didn't pass tech? Wadded their bikes (or themselves) earlier in the weekend?
...just kidding
Mostly people that ran Round 1 or 2 and didn't show for 3 - For example I am DNS for round 2 this year because I crashed the Saturday and couldn't race the Sunday but mostly is people not showing up.