I understand your question better.
The answer is essentially that, at the time the evacuation was launched in 2006, there was no way for Canadian nationals to leave Lebanon on commercial transportation. As my colleague Mr. Beaulieu explained, dozens, if not hundreds, of flights a day are leaving Beirut right now.
The port and the airport are operational. Central transportation networks still exist and are operational, so everyone can leave the country by commercial means, which is more economical as well as safer.