Re: Quicker to re-org than build a datacenter, also network
and probably have all sorts of hedging strategies that give them an effective price well under that of retail.
I work in the energy sector, I can assure you that your presumptions are right about big power consumers purchasing wholesale and hedging themselves are 100% right. But that actually makes my argument stronger because these big consumers are exposed to the full heat of the wholesale power market, and (again, unlike domestic users) they take the full pain of DNO charging structures. You can hedge, but that costs money, and in the long term it has to net off - a bit like domestic car insurance, that on a long term basis has to cover the average claim cost and turn a profit for the insurer).
The price they pay may or may not be under the retail level, the key driver is the profile of their demand. If data centre demand had a similar load profile to overall electricity system demand, they'd pay a very similar price to retail, if they have flat demand curve its a lot cheaper, if they can bias usage to off peak then they'll have really cheap power.
That is, until the ever growing renewable generation inputs start to become the wholesale price setter. Then your wholesale price becomes partially randomised, and any fixed demand profile is worth less than a responsive demand profile. So you'd get much cheaper average power prices for a data centre that agreed to stop running when there was no wind, for example, but the overall economics of that data centre might be a real problem for the owners.