We, as humans, naturally try to optimize for the lowest energy output. Most people, when strictly externally motivated, will take the easiest path. People prefer to sit rather than stand, prefer to watch TV rather than do yard work etc. For those without ample job security, competition creates a bulwark against this by forcing people to try harder in order to get a reasonable level of security. Those who already have that job security (in government positions, for example) revert to that "lowest level of acceptable effort", which tends to be a bit lower without the added job security pressure.

Of course, there's always those few who are intrinsically motivated and highly conscientious that try hard no matter the circumstances.