The basics are: the giant racetrack corporations (CDI) boast record earnings and are flush with cash, while racetrack laborers including hot walkers ($5/horse or $200-$300/week), grooms ($100/horse/week or $400-$500/week), and exercise riders ($15/horse or $500-$700/week) are making EXACTLY the same wages as 15 years ago. The vast majority of the laborers do not own a home, do not have health insurance and do not have any savings.
This problem is not all due to high employment taxes, and it's not due to trainers being cheap because most trainers are as broke as their employees. Of course there are exceptions with the few stables at the highest end with the "star" horses, but I'm talking about the proverbial 99%. I don't mean to pick on Churchill Downs and CDI but those are the racetrack entities that I am most familiar with.