In fact the AMCA allow them on 250's at 13 and if there is a case to be made for a youth to use a larger than a 250 the club can write to the AMCA who will then actually listen to the case, unlike some.
The other ACU sports have youth on over 125's and they actually get to race wheel to wheel in some of them, unlike us, one in a section at a time, at mostly a slow speed, makes you wonder why, unlike some.