Insurgents in the Middle East are basically making fertilizer bombs and using hand-me-down rifles from whatever organization that's supplying them and look at what they've accomplished. We've had a heavy presence in that area for how long now and we still don't have everything under wraps?
Tanks are useless in an urban setting and it's not like civilians would hop into their Escalade and try to take on a tank in an open field, where the tank is actually useful. Helicopters have serious limitations, and you don't use RPGs against humans.
Less video game logic, more real life logic please