Because of the way the war was conducted. We tried to win the hearts and minds of the people. What needed to be done was to pound our way clear with air strikes so that they fled before we got there.
And the oil fields arent difficult to rebuild. The pumps are not high tech.
We did bomb the hell out of the military. We sustained many of those casualties in battle. Even if we'd flattened Baghdad, we still would have incurred thousands of casualties.
The ONLY thing that matters in the middle east are the oil fields. It's a fantasy to think we could take and control the oil fields and infrastructure without engaging in heavy casualties. We would be under constant attack.
But Trump offers easy answers. And people want to easy answers to complex questions.
Bullshit...
We could take and hold the oil fields with ease.
Simple no fly zones and no go zones surrounding them would do the trick.
Once you beat down their military who's going to be able to kick you out?