Why is the price tag more important than the technical details? A diamond and gold encrusted Raspberry Pi in a large warehouse could cost 2.2 billion...
Yes, it could. And if such a Raspberry Pi would exist, much like the data center designs of the largest providers in the world, you would know very little about it for security reasons.
The price tag is more important in this case because it probably *does* reflect the scale and possible power of the project. It's not likely to be being expensive for the sake of being expensive
The hypothetical Raspberry Pi isn't a good comparison, since it was contrived for the sake of being expensive and none of that expense has much effect on the core function. Real-world examples of such devices- i.e. much, *much* cheaper devices with masses of expensive trim glued on (such as "the world's first Arab supercar", (*) Vertu phones et al) would only ever be made as status symbols, so they're not likely to be kept secret, and the type of people who own them would probably be able to keep them secure when not in use (**), you just lock them away.
By contrast, the data centre is expensive for a reason, serves a purpose and can't be locked away. Not really that good a comparison.
(*) Where I already criticised the ludicrous contrived expense of such tacky bling-ified items by pointint out that one could make the world's most expensive car by gluing the Koh-i-Noor diamond to an ageing Vauxhall Corsa, yet its "value" would say sod all about its core function as a car itself.
(**) "In use" being when they want to impress someone who's as much of a bell-end as they are, or lure some gold-digger into bed.