I used to work 6 days a week at a high end h/j barn that housed 60 horses. I'd clean all the stalls, turn in and bring out horses, water, clean out the tack rooms, sweep and clean all the barns, lunge horses, wrap, tack up, basically everything under the sun except feed (they had someone else do that, but when she called in sick I had to do that too), all during our brutal CT winters. I was making the CT minimum wage, $8 an hour, and I worked around 10 hours a day. That was hard work. I only lasted about 6 months. Your daughter should be making at least $10 dollars an hour, depending on where you live. It sounds like she is being seriously swindled. Now I have a job taking care of 2 horses for $15 bucks an hour, but I lucked out with that.
I've spent most of my life riding horses. The rest I've just wasted.