HAHA It's a shame that America do it so badly then. In Vietnam the Americans retreat and come back in shame and defeat to the whoops and cheers of the unbeaten Vietcong. In Iraq they cower inside the green zone too terrified to venture out.
America said they would get Bin Laden and even failed to get him, he mocks and taunts them daily.
America is only successful at dropping bombs and killing civilians. When it comes to "on the trenches" warfare you've failed every single time and the world sniggers at your Keystone Cops attempts to conquer.
Everything America does backfires and ends in yet more humiliation for this glass-jawed "champ" 
see, this is where you are wrong, you are looking are thing from a myopic point of view!
1. bombs are cheap, the media fallout from soldiers dieing is expensive, and so we use what is cheapest.
2. The goal(s) in Iraq were oil fields and expanding the military budget and try to jump start a slowing economy.
3. Keeping bin laden alive is good for America, he gives us a single focal point. When he ceases to be useful in that capacity he will be "captured".
4. Vietnam was a shit hole, is a shit hole and will continue to be a shit hole. Yet, the army can use it as a battle cry.
I am bored explaining simple subterfuge to you.