To make the point, let me turn the question around: if management is easier and pays more, why don't more programmers choose management?
The answer is that it's not necessarily easy to land a management job, whereas there's often work for programmers to do (though programmers may need to do consulting and travel around or something).
What happens is that business types get comfortable communicating with specific managers, and then they don't want to spend time building rapport with new managers. Great if you're that one manager, but not necessarily good for the 5 that are stuck trying to apply as a manager while unemployed.
(I'm sure it's more complex than this, but I believe the above describes a significant factor.)