Just because they are not covered by the GC doesnt mean that you should give no rights to them. People make mistakes and the law is there to protect the innocently accused. This isn't being followed. A country like the US that wants to be responsible should first do so by leading by example and acting responsibly rather than telling everyone else what to do and not following their own advice.
Also let me put this to you. America officially declared war on terrorism, so isn't anyone who is caught as a terrorist by definition a POW?