running in your grade

It amazes me to see dogs running above there grade every day of the week all around Ireland's tracks,i was just looking at one bitch in particular who will remain nameless she has 11 races on her card with her best performance in an a5 race a second place a2 run in only her third race;she was unfortunate to get caught in such a hot race but we all have been there.
She then has to run in a2 class which is competitive enough but is entered in an a1/a2 sweep.... after 6 more races still no win but her placings and times would have allowed her to be back graded to a3 ... unlucky you could say but instead she runs in the hottest competition for bitches in the country...the oaks in shelbourne park where she runs a3/a4 times in the first 2 rounds
so now we have a bitch with 11 races on her card and no win...now some would say this is unlucky but i would say its bad placing with a little luck and some better placing she could easily have 3 or 4 wins on her card
its hard enough to win races in Ireland without running above your grade.
So why do people do it????