SJC wrote:The competitor could still be made to stand around waiting for a long time before they are allowed to start, which doesn't seem particularly fair..
There is no universally 'fair' solution, because the only 'fair' solution was them starting at the right time: somebody is going to have something 'unfair' happen to them. By doing it any other way though, you're then unfair to more than one person. Least damage.
I personally would stick with the system, that you take the next available start slot, and if it's an organiser error your time will then start from that time (OK, so you might have to wait), and if not, the clock is running. It's rough, and sometimes the reason one is late is completely out of one's hands, but just have to roll with it. Hopefully the organisers will build in enough late start slots (not always feasible). At least one can start late: some sports the race is done and dusted if you turn up after the start time!