Consider the scandal if the United States Army paid bribes to their enemy for safe passage of military convoys. In effect, that is what is happening now in Afghanistan. It probably happened in Iraq, too.
The United States sub-contracts out much of the logistical aspects of war to private corporations nowadays. Privatizing war has many advantages as long as you don't care who wins. It makes war good business and popular among the chamber-of-commerce types; instead of being taxed to pay the salaries of grunts driving trucks now the grunts are being taxed to pay executives. It removes the boring parts of warfare so the generals can concentrate on fun stuff like killing folk and blowing shit up.
Soldiers want a war to end quickly, contractors want the war to go on forever because once it ends they are no longer getting paid. The contractors, being mercenary, don't care who wins. Paying bribes to the enemy is a more profitable alternative to providing armed escorts. That the Taliban uses US Government money laundered through contractors to buy weapons and explosives that kill US soldiers is simply the cost of doing business.