I'm not certain, but I think the key word is agent

Travel agents can claim that in selling Alitalia's product, they are acting as an agent for Alitalia and are not responsible for any errors caused by Alitalia (in this case the invalid fare). Therefore, in the event of a subsequent dispute the liability would lie with the provider (Alitalia) and not the agent, thus allowing the agent to legally pass the buck.

Obviously, the legal responsibility of the agent and the moral responsibility are two different things...