... It's clear Apple CAN track a device if the person who lost it is (or was) powerful enough because they have done it.
Not quite.
Law enforcement CAN compel Apple to assist with an investigation of crime. The police will so if the person who lost it is (or was) powerful enough because they have done it.
If you are (or were) "powerful enough" to persuade law enforcement to commit sufficient resources to track down your stolen iPhone, I'm sure Apple will extend the same courtesy to them as they did the Palo Alto police.
Apple's legal authority to act autonomously in crime investigation is limited to its own interests - thefts of their own physical or intellectual property are two examples. They cannot and will not intervene in criminal activity involving third parties, such as the theft of your iPhone or any other property that is not theirs. To do so would violate the privacy rights of others and would invite a torrent of legal challenges, all of which they would be certain to lose.
Note the article above.
Noted. Apparently you did not read the report linked in the article you cited: Apple cooperated with law enforcement. They were legally obligated to do so. If they had refused, the case would have already been the subject of a major media frenzy, instead of a few paragraphs on page 3 of the New York Post.
In a related case, one company did refuse to cooperate with law enforcement. Read FBI vs. Google... in a real newspaper. Apple is probably content to sit on the sidelines and watch Google fight this one.