It doesn't, all it takes is patience or elbow grease.
That being said, using monetary rewards as incentives have been mentioned in the past, though mostly on a hypothetical level.
Unfortunately the time required to do a
great aircraft would be prohibitively expensive if it would be done with a pay comparable to an ordinary job. A commercial grade aircraft for Microsoft Flight Simulator or X-Plane at the other hand could have several hundreds or perhaps several thousands of buyers to take the cost.
One of the forum topics:
Bounties for developers; Wiki article from one of the times:
Bounty(Overview).