But the terrorist attacks took place in the United States, not Canada.

AA and UA were at severe risk of going bankrupt because 2 planes of each airline were destroyed to "send a message". US was at severe risk of going bankrupt because DCA (prime source of their high yield pax) was shut down for over a month and still has yet to be restored to 100% of the service prior to 9/11. WN was at severe risk of significant financial loss because they cater to mostly leisure pax who cancelled trips right after the attacks. The impact on the American economy would have been far greater than the amount of aid given had the government not done anything.

Air Canada was not at risk of going bankrupt. That's why they didn't need the same level of aid given to US carriers. I'm sure if they were at risk, the government would've stepped in.