<p>Because you’re probably a senior or junior if you’re prowling these boards? ;)</p>
<p>but if you’re talking about a 10th grader - it is (i think) easier to score >100 on AMC 12 than >120 on AMC10. Since sophomores and below can get into AIME by a floor score, they don’t have to worry about the AMC12 + 10*AIME index, so as long as they qualify for AIME (even with low AMC12 score), they have a good chance of advancing if they beat the floor.</p>