Well While I Find it highly unrealistic A lot of the people I see with "Urban BOB's" believe the fact that they can live and survive in a derelict city after a major disaster.
Eh, it depends on the disaster. Can you provide an example (preferably a real example) of the type of disaster you imagine?
Given the fires in southern California fires a couple years ago, hiking to go bug out in the boonies would have been a very bad idea. Likewise, given the recent gas explosion in San Bruno, hiking to go bug out in the boonies would have been a bad idea. A better move would be to have cash and credit cards in your bug out bag and rent a hotel room far away from the fire.
Looking at Katrina in retrospect, I would do everything I could to avoid using the Superdome as a shelter. Unfortunately, the Superdome is something a lot of people had to use.