That is a large animal, high strung to run better, trying to be handled by a weak person.
I don't know this one in particular. Most of the time, at this young age, we mostly see horses so gentle and well trained there is little effort at all required. There are exceptions certainly, but we have even seen kids fall off and the horse complete the pattern without the rider.
The majority at this lower competitive level (as this event was) are not that high strung horse (like my daughter's freakout horse).
I know it is done all the time, but the odds are there that calamity is more prone when a youngster is the handler rather than a mature person.
My wife is on the Houston Livestock Show every year as a volunteer, so we see it frequently.
Houston is not a typical youth rodeo. And that is a hard event most won't consider going to. There is too much noise and commotion, the horses tend to get all jacked up. Even Fort Bend County Fair has gotten bad with all the high noise level and no real room to warm up away from a crowd. Far different atmosphere than at the Buddy and Edile Lightsey Arena at the Burleson County Fair Grounds in Caldwell.