You got one. It was Bush’s first action when he heard the news, calling Chretien to offer sympathy and full cooperation in an investigation. Within a couple of hours, the White House had offered a second apology in writing.
Bush’s goof was not broadcasting an apology to the Canadian people (figuring Chretien would convey the news).
You can still be upset that he did not express the “proper” apology in the forum that you would deem “correct.” (And I would support you in that anger, since he has demonstrated a fairly clueless attitude in that regard.*) However, you overstate your case when you imply he ignored the incident.
*Go back and look at American reaction to his statements from 9/11 through the evening of 9/13: he took a lot of flak for his bumbling, ill-considered words at the time. It was not until he could get someone to put the words on paper in front of him on the evening of 9/13 that people began to say (often grudgingly) that he was beginning to sound Presidential.
As a PR person, he is no R. Reagan–more like his daddy with bad manners.