If the customer pays for goods and services, their entitled to receive what they paid for. If the airline is unable to fulfill their obligation to provide the service, then it is then, their responsibility to refund the payment or to offer an alternative service to fulfill the customers need. If there is a term in the service agreement to request a refund within the certain time frame designated by the airline itself, I see no issue with this. It’s not an uncommon practice and benefits both sides of a purchase. While I can understand the extent of which this would impact airlines, their revenue from ticket sales is not the responsibility of their consumer base. By not doing so, it can severely impact the lives of those who were in need of the flight and/or money to travel if the flight was not available.