Paul, you hit the nail right on the head - it's all down to *power* and the fastest way to achieve phase transition. The highest rated 115V kettle I’ve come across here is 1500W with the majority on offer being only 1000W – I saw one rated at 750W! Morning tea is a must and time is short at that time of day. One cannot beat 3kW of grunt to raise 2 pints of cold water to boiling point in about a minute.
Guys, thanks for your replies. On the same vein I see that 210-6 (a) (2) restricts voltage at receptacles in dwelling units to no more than 120V if the cord and plug-connected loads are less than 1440 volt-amps (or ¼ hp). How does one satisfy the AHJ that this is the case (i.e. a 3kW kettle) – after all, once installed in a new bare house the occupant could plug any 240V device into it.