As the OP picked some examples from… somewhere (I can’t find any specific reference beyond ‘postings’), I’d like to submit this thread from around the same time frame: http://talk.collegeconfidential.com/sat-act-tests-test-preparation/1715146-what-was-your-sat-vs-act-score.html
In that thread, you’ll find correlations of 24 ACT <=> 2050 SAT, 27 ACT <=> 2090 SAT, 30 ACT <=> 2180 SAT which should adequately refute the three examples OP provided.
@texaspg - While it is true that the number of students who’ve scored a 36 has doubled in 3 years, from 704 to 1407, this still represents less than 1 student in 1300. You’re letting the tail wag the dog. The meaningful number is the mean score, which has gone from 21.1 in 2011 to … drumroll… 21.0 in 2014. In other words, no significant change at all. (http://upload.wikimedia.org/wikipedia/commons/6/6f/Historical_Average_ACT_Scores.svg)
Please bear in mind that correlation is not equivalence. The SAT and ACT are different tests, covering different facets and under different modalities. To make a strained analogy… while good athletes may do well in both baseball and football, it shouldn’t surprise anyone that some players do much better in one sport over the other.
Some students do better on the SAT, some on the ACT, many do roughly equivalent on both. Welcome to statistics.