The Young Rider program for riders is for ages 16-21, and it's for riders who are already at a fairly high level of achievement; in Eventing, you have to be competing at preliminary level (3'7" obstacles).
If you are allergic to a thing, it is best not to put that thing in your mouth, particularly if the thing is cats. - Lemony Snicket
Is this a local club? The two most popular youth organizations are Pony Club and 4-H. The quality of both programs varies based upon the organizers and instruction in the area.
Separately, the FEI is the governing body for international-level competition in jumpers, dressage, eventing, driving, endurance, vaulting, reining and para-dressage. It licenses competitions at the top levels of each sport, for adult competitors. Additionally, the FEI holds competitions at elite levels for children as well, grouped based on age. The levels for dressage are FEI Pony (12-16 y/o), FEI Childrens (12-14 y/o), FEI Juniors (14-18 y/o), and FEI Young Riders (16-21 y/o). It isn't a program or organization, just a level that a very advanced child can opt to compete in at certain competitions.
Perhaps this is an "image problem" of sorts with Young Riders, but I was pretty much under the impression that it is primarily for fast-track, well-heeled young eventers with horses already doing Prelim and up.
Pony Club is probably way more suitable for a younger kid.
DW, I don't know about other areas, but the Area 2 program is under new "management" (for lack of a better word) this year and the ladies who are in charge are making a BIG push to make it more all inclusive to ALL young riders, and not just the kiddos working toward the one and two star NAYRC teams. There's been a couple of YRAP clinics and a YRAP CT locally already this spring, and I know a few kids who've attended. Some are a year or two away of being team material (novice/training kids or kids too young just yet), but they are getting good instruction and camaraderie from participating. Like I said, this is specific to Area 2. Other areas may not be as active.
Deltawave-Not all YR are well heeled. It is a a slightly more advanced division than the standard Prelim designed to encourage developing riders. Some buy already made horses, but I can also think of some who brought their horses up the levels. The OP needs to get to the USEA web site, and perhaps they can learn more there. It really isn't an organization but a goal-as in "to make Young Riders" (team).
And, yes, USPC is extremely beneficial to young developing riders.
Some riders change their horse, they change their saddle, they change their teacher; they never change themselves.