Very good point BB, I remember in August 2001, on the Millennium, the ship was enroute to Alexandria, Eqypt. Due to the propulsion system on that class ship, which is it seems constantly experiencing problems, we were told we were arriving 2 hours late in to Alexandria.
Passengers with ships tours had nothing to worry about, the tours to Cairo were still a go, those to Luxor were cancelled and the passengers re-booked, if they so desired, on Cairo tours.
Those who did independent tours, had absolutely no idea if their guides would be waiting. Some were, some were not.
Also, of those who did independent tours, the company they used, which was supposed to have an english speaking guide with them, left the guide in Cairo, the driver spoke no english and they got stuck in traffic and made it back to the Millennium with only minutes to spare.