I think this is worse than hitting a horse when not in contention of running in the first five. Not being in contention is a judgment call which could be based on a number of factors i.e. how does the horse feel, have you ridden the horse before, does it run on from back in the field, what is the start number in this campaign, how has the horse trained and eaten this week, is today's race the optimum distance, is the trainer trying different tactics etc.
A well trained horse with ability is a pleasure for a jockey to ride and may need little whipping. For the others make sure you have a savvy jockey who knows how to hit, where to hit and how to count.
Is it really that hard? There are official eyes, cameras and vets to enforce the rules. If jockeys want to ride and be paid, abide by those rules, or suffer the consequences.