In a poor village such as the one where Kino and his family lived, a canoe would be something of extremely great value.  The author describes Kino's own canoe as "the one thing of value he owned in the world...Kino's grandfather had brought it from Nayarit, and he had given it to Kino's father, and so it had come to Kino...it was at once property and source of food...it is the bulwark against starvation" (Chapter 2).  To take one of his neighbor's canoes would have been unthinkable for Kino, because to do so would have been to take their sole means of making a living, and most likely, the one thing of value they would have in the world.