On purchasing servers; I don’t know about Google specifically, but most media partners I’ve worked with doesn’t have global acquisition as an option for hardwares — not because they don’t have the purchase power/volume, but rather the vendors have region specific distributors with their own sales teams and pricing. Even if you have the personal contacts of VPs high up the chain, someone from IBM China cannot even sell to companies in Canada, and vice versa, for example.
On people side of things… With YouTube specifically, you’re also not only dealing with their own DC but getting their hardware into local ISPs centres. Logistics around that is not something cheap remote labor can arrange, need actual boots on the ground to facilitate.
Ad sales is also something that’s kind of localized. YouTube has American teams selling American creator inventories for example. Not something that’s outsourced out.
So yea… Although from the outset it’s all just “YouTube.com”, there’s actually a lot of localized touch points that creates different costs to provide service in different regions.