Those are just the most notable incidents. There have been dozens of others over the past 10 years, each bringing in hundreds of people who spend money for cars and gas and meals and motels and T-shirts and souvenirs of their adventure. It is not an inconsiderable amount of money. Even on the cheap it costs several hundred dollars to indulge in one of these chases, and most bird watchers do not do it on the cheap. Bird watchers may be crazy, but they are well-heeled.
Rarity increases the value of everything.
After a bird watcher has spent a few seasons in the sun, he has seen all the local birds. To see something new, he has to travel farther and farther afield. Before long, his chances of seeing a new bird anywhere has faded to near invisibility. The why is complicated and irrelevant to this discussion. For each the answer is slightly different, but what matters is that the emergency travel bag is packed and sitting by the door twenty-four hours a day, every day of the year.