School bus speeding not unusual

See http://www.nytimes.com/2016/11/22/us/chattanooga-school-bus-crash.html.

I drove buses for three years plus at Medicine Lake Lines/Ryder.  I made every effort to go at the speed limit as determined by conditions, including speed limit signs.  If I was in a convoy on a charter, often the other drivers were pulling away from me or complaining I was going go slow.

I don’t understand why drivers would want to speed.  After all, if they go slower they’ll get more hours!