At no time have I said that Halliburton is the only company capable of doing the job. You are the one who already has this job awarded to Halliburton - which of course is not the case - but no doubt you will continue to spout that as existing fact.
In any post-war reconstruction, potentially the sheer sized and complexity of the contracts would be enormous. Who would you award them to Bobert? How many contracts would you award, who would determine the interfaces and division of those contracts Bobert? And most importantly who and how would you co-ordinate it?
Now you could, as you seem to suggest, have a multitude of different smaller companies working on the various parts of the work under control of the government. To do this each part of the work would have to go through a bidding and tendering phase, with it's subsequent clarification phase. Contract award and establishment of Client (Government) site teams to follow the work through for each contractor. The government would then have to have an overall Project Team to oversee the whole thing. In other words you would have massive duplication of effort with its associated costs and scope for error consequent foul-ups.
On the other hand you could issue the work as a lump sum EPCI contract - that's one contract Bobert, just one. The responsibility for running the job goes to the Contractor - he's better at it than than any government official or civil servant. It is far cheaper to run and monitor. It's far more efficient and cost effective.
You seem to believe that having the government in control is somehow beneficial. Governments and their civil servants are notoriously non-commercial in outlook and experience, they are far from efficient. I can think of quite a few government run projects that were complete unmitigated disasters in terms of schedule, cost and end product. In all those cases they would have been far better leaving it to the people who know what they are doing - the contractors.