That's the network transformers. Homes usually get single-phase 230V, while larger users get three-phase 400V.
Systems which run a higher consumer voltage (e.g. 230V) will tend to use higher kVA transformers compared to the American system (~110V).
I believe this is because it is feasible to run longer cables when using higher voltage (higher voltage -> lower current -> lower thermal losses per metre of cable), hence it is economical to use fewer, larger transformers in a higher voltage system vs. a lower voltage system.
However, even here the network transformers do get three-phase.