Ars Technica has a terrific article on the nature and process of discovery in science. It describes the role of what is called "placeholder", where we assign to something, and giving it a name, of a phenomena or idea that we could not yet verify, or has any empirical evidence.
I think a lot of people, especially those who are outside of science, do not understand that it often takes a lot of time, a lot of observations, and a lot of discussion back-and-forth, before we can actually proclaim something to be well-known and come to a consensus. And when something is as difficult to test and study, such as dark matter and dark energy, the length of time involved will be even longer. And also consider that, for science to claim that we understand or have discovered something, the criteria for such claim is extremely stringent! Unlike politicians and TV personalities that seem to have no problem proclaiming that such-and-such will improve our lives or create jobs, etc. with utter certainty, science requires a lot of verification for something to be accepted as well-understood. Not only must the phenomenon be verified to be happening, but a mechanism to describe how it happened must also be in place. So it requires both experimental and theoretical aspects of the phenomenon to agree with each other. This is not easy!