Manufacturer specifically asks customer to keep it informed where the equipment is physically located, and then prepositions spares to appropriate depots in order to meet the contractual requirement established when the customer paid them often a large amount of money for 4-hour Same Day (24x7x365) coverage for that device.
This isn't how hyperscale folks operate for the same reason Fortune 100's rarely take out anything more than third-party coverage when their employees rent vehicles, it becomes an actuarial decision, the # of 'Advance Replacement' warranty contracts and the $ involved, vs. buying a % of spares and keeping those in the datacenter then RMA'ing the defective component for refund/replace (on a 3-5 week turnaround time).
tl;dr - Operating 100-500 servers you should likely pay Dell and they'll ship you the spare and a technician to install it, operating >500 servers and you should do the sums and make the best decision for your business, operating >5000 servers and you probably want to just 'cold spare' and replace yourself.
Now, these contracts aren't like your average SaaS offering. We had a sales rep and the terms of the support contract were personalized to our needs. I imagine some locations were offered better terms for 4 hour service than others.
As I learned long ago, never say no to a customer request. Just provide a quote high enough to make it worthwhile.
That said I suspect most enterprises pay too much; as in their money might be better spent buying triple mirroring on a JBOD rather than a platinum service contract with a fancy all in one high end RAID-y machine.