They're not actually accessible with 'only one set of keys' in my experience.
replyYou actually have to present your photo ID at the site entry gatehouse, then again to the building entry guard (who will also check you have a work permit and a site-specific safety induction) then you swipe a badge at a turnstile to get from reception into the stairwell, then swipe your badge at a door to get into the relevant floor, then swipe your badge and key in a code to enter the room with the cages then you use the key.
Other than for certain nuclear missile launches[1], that only happens in the movies.
reply[1] https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact...
I dont know how it is in the datacentre industry, but certainly in other industries that is how its done for anything truly mission critical and also easily tampered with.
replyI guess it shows very few care enough to pay enough to make that a reasonable upgrade.