Agreed, they don't.
Minimum Checkin Time is 45 minutes before scheduled departure time for Canada flights and she says she was denied her checkin at 60 minutes.

IMO poor reporting with inadequate fact gathering. However, we all know that Air Canada intentionally over sells its flights. The fact that she was put up in a hotel, suggests that she was intentionally denied boarding.

I wish that more relevant facts were declared such as;
- Fare class. If she was on the lowest of Tango fares, then she would have easily been bounced.
- Did she pay to sit together with her family, or just expect that the airline should give her family complimentary seat assignments?

I think we all are willing to give AC the benefit of the doubt when customers purchase on price and don't purchase seats etc. However, and it's a major irritant I have with Canada's airlines, is that they do not warn their customers of the consequences of buying a cheap seat. Instead, the airlines sell them illusions of comfort and care. There needs to be more transparency and honesty from all of the airlines when it comes to the fares purchased. There is a moral duty to warn that the lowest fare pax are the pax who get bumped. They also need to be told that if they want to sit together, they must pay. I don't know why the airlines refuse to be clear about this. As such, they feed the unrealistic expectations and are the authors of their own negative PR.