The sheer amount of metal on every rack makes DCs very dense

It's either 100lb or 100Kg, with a direct hit on a dense centre, it would damage a lot of racks, but if it's oblique, or indirect, impartial, the damage could be less pronounced. They could also be misrepresenting by diminishing the damage as there's a lot of information suppression going on.

I wonder if you can uncover where the data center is just by using ping command.

Big tech's love for cheap labor is a great mechanism for finding where all their most valuable assets are and mapping out any and all vulnerabilities. I imagine state actors are applying to any and all low paying jobs that have seemingly juicy job requirements and feeling out details during interviews. Even better if you offer to accept a salary far below standard rates and actually get the job.

While probably not a state agent, I've personally done online interviews with some people that were clearly lying about everything and trying to feel out details about the company. People claiming to live in our country and being citizens but having little ability with the language, saying they would love to come to our city but it's a bit far, saying they graduated from a major university but being unable to describe anything about the town (with their resume mentioning graduating from a different university, and their LinkedIn a different university from either), random people moving around and arguing in the background, all their work was with random crypto businesses that shut down within months. I had to stop my coworkers from saying too much. I had to convince them why hiring that person for remote work and giving them access to our servers was a bad idea. There are without a doubt companies giving similar people physical access to their hardware. And there are undoubtedly people who practice interviewing to better deceive companies.

Just look on satellites for giant buildings with no cars or semi trailers parked in the parking lots.

I wonder if data centers will have to start doubling as automobile junkyards to conceal themselves.

You can be secretive all you want, but it's extremely difficult to hide massive heat exchanging systems and/or generators from aerial/space photography. Particularly at the scale of an AWS-like datacenter.

Building a fully camouflaged datacenter could be done at much greater cost, but you still can't hide its thermal emissions from infrared.