<p>Could it be sheer numbers? Mexicans are the largest Hispanic group in the US and you could say they have been here since day one. What would you expect? </p>
<p>In any case, unless you are URM with top stats your chances of going to the top schools is very low. Today there are plenty of URMs that can compete with anybody academically (and just like anybody else, not be accepted to an Ivy).</p>