They have two now apparently, one in California and one in Texas. But public information on these is sparse, I've not been able to find out much about them. This seems uncharacteristic for an Elon Musk company; Musk and SpaceX talk at length about their rockets for instance. There is a different level of public interest between rockets and boring, which might explain why there is more public information about the rockets. Still, I'm not surprised people are skeptical (or ignorant to the existence) of these bores.
>> There is a different level of public interest between rockets and boring
Or the simple practicalities of the later. I'm a member of the public. What I know of the boring project comes from the youtube videos of the traffic jams in the current Vegas tesla tunnel project. Building an underground tunnel to bypass above-ground traffic problems worked only on the Simpsons (Stonecutter episode). In the real world such tunnels are just another 1-lane road subject to all the same problems as they would on the surface, plus a bunch of bonus problems. It isn't interesting because it isn't practical.
