Walking down the stair, not holding handrail. Sending text messenger while driving, letting the kids to play around the escalator, are “Complacency”. In Thai, it a little bit lost in translation to “satisfaction”. Read more explanation here.
When we are in the mode “It is okay”, we ignore safety precautions. Why is that? This is hard to explain for those who have been doing somethings dangerous but never have any accident. All I can say is that “not your turn yet”.
In defensive driving training program, distraction while driving, speeding and maintaining narrow space when following other cars are repetitively emphasized. Believe me or not, out side of the room, all participants does those thing. 
Complacency when combined with “Violation” is even worse. Example, you are approaching an intersection. The light is now turning from green to yellow. You know that it is going to be red in few second. Instead of slowing down, you accelerate through the intersection. At the same moment, on the other side, there is another car is also jumping out through the red light because the driver think it will be green in few second. Now can you imagine. In fact, people with the mode of “Complacency” will never be able to imagine such a thing. Trust Me.