I live outside of the US for most of the year and can say that my driver's license is not at all useless as an ID.
In fact, I have been at police checkpoints in two countries where they refused to see my passport and specifically requested that I present my driver's license - but these were both when I was driving, of course.
They will actually sometimes accept them here in Vietnam for various things but Vietnam is still kind of the wild west legally. Certainly not a good idea to count on it.