in the old days they picked by eye, no cameras no video. you were lucky to get top six listed. the good new was that there always 20 guys who claimed to have placed in the top ten
don't feel so bad about being listed as dnf, i placed 7th or 8th in the 35+ race and should have got some sort of prize but i was not able to check the unofficial results as i was racing the next race and when i was done the results were official and to late to change. they didn't have me listed at all.