[stan_rogers]

For resistive loads (like the heating element in a kettle), half the voltage gives you a quarter of the power. (Electric kettles work just fine on 110/120; they just haven't been a thing in the US. They've been ubiquitous in Canada, although they've been pushed aside somewhat by drip coffee makers. You just need a lower-resistance heating element than would be practical with 220/240.)

[wongarsu]

Electric kettles in the US typically are 1000W-1500W, while in Europe any kettle is 2000W-2800W. This is simply because houses are typically wired with outlets for 10A-16A everywhere, regardless of grid voltage.

That ofc makes electric kettles much less useful in countries with 110V grid. It also keeps stovetop kettles relevant in these counties, since stoves don't suffer power limitations.

[oftenwrong]

Houses in the US are typically wired with 240v split phase, so nothing is stopping a mad lad from installing a 240v outlet in their kitchen, and running a kettle from it.