Datacentres can in theory reduce bills.

They're a large, mostly well-behaved grid load which lets you spread fixed costs over more units of electricity.

The problems start when they are being built by well connected entities that can leverage their power to simply demand that other people pay more to give them a discount.

Very similar to the shopping around factories do. Usually a factory brings jobs and other good stuff, but you don't get the factory unless you do X, Y and Z in competition with all the other possible locations. That can lead to a winners curse where you're effectively subsidizing the factory and losing out overall if you "win" the auction.

And yet here we are, still subsidizing steelworks in England, and Scottish people are paying the cost in their electricity bills.

Scotland's abundant local energy resources should be spent on things that actually benefit Scotland and provide jobs.

Scotland is not a member of the EU since brexit.

More difficult to built, more difficult to get permission, ironically, and presumably the datacenters are planning to employ some people so they'll want to live at least somewhat nearby.

Too easy to destroy if they're outside of population centers - soon they'll be building them under hospitals and orphanages