You have very strong opinions but that does not make them facts. My daughter was in community college at 13 and was a bit intimidated being with older kids at first. She made friends she has stayed in contact with 10 years later. She was well loved by her professors, especially English, History & acting, all of whom wrote her stellar recommendations for college. She was uniformly praised for being forthright, responsible and thorough in her presentations & reports.
Where is she in your universe of higgldey, piggildy, rambunctious teenagers?
People make those ageist generalizations all the time. My kids went to Shakespeare plays from age 4 or 5, to concerts, NY theatre, dance performances, anything we could find to broaden their experience. Frequently we were stopped leaving the shows to be complemented on their perfect behavior. My children in private commented on the bad behavior of the adults who whispered, opened candy etc. Its all a matter of explanation, expectations and setting an example.
And that opening the testing opportunity to children of 13-14 will be extremely expensive. These tests have to be produced, administered, and scored. That costs money. Tax payer money.