Datacenters are very low key places. They're all around you and your not aware. Owners go through great lengths to keep them hush-hush and control access. It's not something some rando would know the location of.
Also, the "evacuation beacon" required some engineering to be installed on a RV (?) In my opinion, that was an industrial grade annunciator, that would be used at something like an oil refinery to notify workers if there was a toxic / explosive gas leak.
It seemed like many people were aware of the AT&T building before it was reported or any outages, but your point about the loudspeaker is crucial. Thank you for the post!