Most of the examples are where AC has cancelled the flights and is refusing to provide a refund, rather than situations where the customer has voluntarily cancelled.

If a hotel closes, and is unable to provide the service you paid for, they would typically need to give you a refund under general consumer protection laws and principles. If you voluntarily cancel but the hotel is still open and able to provide the service, that's different, and generally you're subject to the cancellation terms or a goodwill policy. Apples and oranges.

AC has cancelled flights and is unable to provide the service that customers have paid for. Yet, even with the DOT and EU laws saying they need to refund fares where they've cancelled flights, they're still dragging their feet and refusing to provide refunds even if they are unable to provide the service the customer paid for.