The bit about kettles in America is a myth Robert, there are kettles in America, just not as many as in the UK, Because the Americans drink more coffee, and of course, in the US there are many more coffee makers, which have a kettle inside them anyway. If you took a UK kettle to the US it would take longer to boil because it was designed to run on 240volts. US kettles and coffee makers are designed to run on 110 volts, and heat water at the same rate that they are dissipating watts, regardless of voltage. I used to have a 12v kettle for my camper van, you needed the engine running to use it without risking a flat battery, but it boiled water on 12v DC just as well as any other kettle, but of course used more current. In the real world, when voltage goes up, an appliance which is dissipating watts, be it a light bulb (incandescent) or a kettle will draw a lower current in amps. Only my camper van had a DC supply, the rest of the world is on AC.For a DC supply, the power consumed is a function of the load resistance and supply voltage. (An AC supply includes reactance, which is frequency dependant with inductance and capacitance having an effect.) P = I x V. Assuming the resistance is constant, changing the voltage from 240 to 110 would drop the current drawn which would drop the power consumed. (Why are there no kettles in america)
Power loss is powerline transmission cables is proportional to I^2 x R. As R is a function of cable length, cross sectional area and material, it's 'fixed'. To reduce loss, the current flowing needs to be reduced, which is achieved by bumping up the supply voltage, hence 11kv.