>Who decides what jobs are available? Who decide who gets which jobs?
Your questions can be answered by looking at what happened in the 1930s. The government decided that things like the triborough bridge and the lincoln tunnel, airports, dams, new schools etc. would be a net benefit to our society.
They were.
>By giving a job instead of money, you are using up a significant chunk of the labor pool.
Yes, it is using up a significant chunk of the labor pool that is currently idle.
>You need an additional chunk to figure out how to allocate it, and are then relying on them to allocate it well.
Exactly like we had in the 1930s with the PWA. Which worked.
>To build something, you are also paying for and using up capital.
Damn right. ZIRP and asset bubbles all over the place are not forming today because we have too little available capital. They happening because we have an excess of it.
>By giving money, people are free to use their time in whatever way is most valuable to them, only using up the resources they need to live, and those resources get allocated by market forces.
Those same market forces that didn't build the triborough bridge or the hoover dam but which did cause a massive overbuild of useless McMansions in Las Vegas and a glut of payday loans?
Sorry, I'm not convinced by arguments that appeal to the dogma that market forces are god and governments always suck at resource allocation. It's a fairy tale.