Late night and early morning airline tickets are cheaper

Most people do not like to travel late at night or early morning since their sleep will get disturbed.
Additionally finding a public transport vehicle like an auto rickshaw is more difficult at night and the charges are also higher. Even at 7 am it is very difficult to find an auto which go to the airport.
For women travelling alone, traveling at late night or early morning is not very safe, since the roads are deserted
So some travelers will be forced to use other travel modes, if the flight timings are not very convenient.