The size of a high-power 60 Hz transformer is prohibitive in weight, both directly (where are you going to put it?) and in impact on price (shipping, amount of

The size of a high-power 60 Hz transformer is prohibitive in weight, both directly (where are you going to put it?) and in impact on price (shipping, amount of metal). It ends up lighter, cheaper, and not much less efficient to do a high-frequency conversion instead, either as a boost directly from the 120V AC or as a DC-DC in the secondary.