If so many people are stranded, why are planes flying with empty seats?
Some flights cancel (don't even leave departure stations), some flights divert to alternates, some flights arrive too late to make connections and some flights get stuck in the penalty box because they can't get a gate. It's called Murphy's Law and most people, especially standby travellers, have back-ups to their back-ups.
Most people are pretty adaptable at finding a way home. Immediately after 9/11, my pharmacist brother-in-law was at a convention a great disteance from his home in NY City. He was able to wrangle a ride home two days later (on 9/13) via FedEx by "escorting" medicine to NY City. I'm an airline captain on a trip and he got home before I did.
In reference to Iceland's Volcanic disruptions, If they absolutely had to get somewhere (and can afford it) many people left the airport they were stuck in and found another way home. Anyone who has travelled even moderately by air over the last twenty years knows when to hold em, when to fold em and when to go get a hotel room.
But the most important point that you make is that experienced travellers do not trust the airlines because the airlines have proven not to be trustworthy. As you have stated in past blogs, it's hard for the customer service agent to intelligently inform passengers when the airline itself doesn't know what's going on. It's equally difficult for airlines to know what's going on when ATC, governments or entire regions don't have a clue about how to handle / deal with Murphy's Law.
Unfortunately, shit happens. If passengers, airlines, governmental agencies and others are dependant upon each other when it does happen, then they'd better discover a process for handling / dealing with the inevitable negotiations, conflicts and confrontations created by Murphy's Law. We're all on this lifeboat together!