How do McGregor’s Theories X and Y and Ouchi’s Theory Z explain worker motivation?

"Douglas McGregor influenced the study of motivation with his formulation of two contrasting sets of assumptions about human nature—designated Theory X and Theory Y. Theory X says people don’t like to work and will avoid it if they can. Because people don’t like to work, they must be controlled, directed, or threatened to get them to make an effort. Theory Y says that people want to be self-directed and will try to accomplish goals that they believe in. Workers can be motivated with positive incentives. McGregor personally believed that Theory Y assumptions describe most employees and that managers seeking to motivate subordinates should develop management practices based on those assumptions. William Ouchi’s Theory Z combines U.S. and Japanese business practices. Theory Z emphasizes long-term employment, slow career development, and group decision-making. The long-term decline of the Japanese economy has resulted in most U.S. firms moving away from Japanese management practices."