No, this isn't about public schools, it's about another kind of education entirely — the training of foreign military and police forces by the US military and the CIA. Even when compared to the success rate of your typical inner-city high school, it's a failure.
How many billions of dollars has the USofA spent "training" the Iraqi army and police forces who promptly abandoned their positions, leaving their US supplied weapons behind, when IS took over Ramadi? How about the half billion or so spent recruiting, training, and arming Syrian "moderates" — 51 of them by best estimates, of whom roughly five still are in the field? Then, just last week, American trained forces in Afghanistan abandoned Kirkuz to Taliban invaders, despite outnumbering their enemy and being better armed. To add insult to injury, military spokespersons have persistently reported glowing success for the training programs, even as graduates turn tail and run away.
Some blame the inadequacy of Iraqi and Afghan officer corps, but it's probably just as well that the USofA can't take responsibility for officer training. Our Western Hemisphere Institute for Security Cooperation (WHINSEC), formerly called the US Army School of the Americas, has been training Latin American military leaders for many years. Its graduates are best known for leading military coups against elected governments and some of the worst human rights abuses on record.
So why do we continue to throw good money after bad in the Middle East? Because "training" seems like a reasonable substitute for boots on the ground. Given that a reprise of the Bush invasions that got us into the mess in the first place would be understandably unpopular, and that just taking what remains of our marbles and going home is not an option, we seem to be trapped in what economists call the "sunk cost fallacy." We'll continue to invest more and more into a losing proposition.