UK Air Chief Marshal has explained the lack of unmanned fighter aircraft, stating that, while technology has progressed tremendously in certain areas, it has not filled the gap “in terms of the manned combat air mission operating in contested, high-intensity airspace against demanding threats.” Technology has not yet created a “path to take the person out of that platform.” The commander stated that while the future air force will continue to move in the direction of unmanned craft, the time when they will be completely unmanned is a complete unknown, given the current state of technological development in that area.
Source: Why an unmanned fighter fleet isn’t yet viable, in the words of Britain’s Air Force chief