Yes clarkey you are right about jockeys getting paid the same rate just for riding in a race but it's a different rate from the flat to the jumps as you pointed out, so the more rides jockeys get, the more money they get and again as you say, they all get a percentage of any winning or place money which in bigger races can be substantial.
So in Bryony Frosts case she gets some decent rides because she is a top female jockey over jumps, and will be making a decent living out of it. UTM