It is not a question of technique, but of medium. The only thing capable of travel at the speed of light is light. The wavelength can vary but not the maximum speed. It is possible that we are missing out on activity at extreme high or low frequencies. There are specific difficulties at using light at those extremes. Why would ET go to such extremes?
Until a distant signal is picked up, it seems silly to me to expect physical presence first.
You argue that they may be way, way ahead of us. But surely not all of them. Some will be going through through a phase of development similar to ours when they transmitted. Just as they may be now picking up our signaling activity, we ought to be picking up that of some similar activity from out there. No?