Elementary kids shouldn't train like middle school kids, middle school kids shouldn't training like high school kids, high school kids shouldn't train like the pros...
The advanced nature or entertainment value from a drill is not a barometer for the skill of the athlete doing it. Appropriate > Advanced
If you are worried your kid isn't doing the advanced or hard stuff, research what is appropriate through different stages of development and why. You could start by reading this blog on various stages of development (How to train your 5 year old ).
For starters, seemly simple movements hardly mean they are easy to do well.You should be concerned if your child is prepubescent and is engaging in the same workout you see high school or pro athletes doing. Hormones are one of many key factors in how you decide what to do with athletes. One example would be that cross sectional muscle fiber cannot produce a mass gain from hypertrophy training until the right influx of hormones are present. Resistance and "weights" are not entirely a bad option for kids but should be implemented appropriately with goals that are realistic and with long term in mind. If a kid can't move cleanly through a range of motion, they certainly shouldn't load it. Establishing a proper range of motion will effect performance far greater than loading a limited or unstable one.
Movement is king and there is no stage of development in which movement shouldn't be the top priority. Even still, ability doesn't ever outweigh stage in development. Don't take simple/appropriate as something interpreting your kids ability. Complex agility drills, "footwork", and other eye wash that requires developed power or central nervous system components are inappropriate. If a kid can't balance on one leg, they hardly need to be maxing out on box jumps or resisted sprints. Even the pros establish correct movement patterns consistently before loading high velocity movements of any nature.
A lot of times "trainers" will get parents to commit to them by letting their kids do things that are "advanced" but inappropriate for their stage of development, because of the parents desire for their child to be advanced- they see this as a better situation because of how good they think their kid is. Bones and tissues remain the same regardless of ability. Certain fundamentals and skills are appropriate at any age and should be visited throughout the entire spectrum of human performance.
Young athletes are building a map with their central nervous system. Everything they do is contributing to where the body is heading as it matures. If the central nervous system is overloaded in any way it will alter the map to protect the athlete from further damage. So, if you think it is cool for a kid to get "pushed hard", keep in mind you are most likely steering their development the exact opposite direction physically, mentally, and socially. If you want a kid that pushes through adversity then raise them right, because beating them up in workouts won't do it.
Nothing counts till varsity.. NOTHING. You are not getting ahead by doing things that alter the proper formation of the central nervous system and all the tissues that follow.
Bobby Stroupe RSCC*D CSCS*D FAFS