Quote from achilles28:
This idea gets kicked around a lot.
The economic fallacy of putting the unemployed to work is it destroys existing private sector jobs.
If the unemployed build a bridge, private sector workers go hungry. So it's a net wash on employment. Except now the project costs more since we're using unskilled labor bureaucratically managed. Costs go up. Quality suffers.
The only type of busy work the unemployed can do without destroying private sector jobs: picking up trash on the highway, rescuing sea turtles, things that aren't critical or helpful to the economy. Which is why doing them wouldn't stimulate the economy. The only benefit is the incentive it provides for the unemployed to get a real job.