A warehouse or factory would have more jobs, but would also bring massive truck loads to the local roads and corresponding pollution. The low staffing of datacenters means that one they are built there is little transportation impact.
And there is almost zero value generated locally.
> A warehouse or factory would have more jobs,
It would add low value-added jobs though (unskilled labor). Datacenters add high value-added jobs (skilled labor).
Only looking at the headcount is shortsighted imho.