Canadian tea drinker checking in. I've used an electric kettle all my life and don't see what the problem is...

Electric kettles are common here even though we use 110V power. I've never timed it, but I think they can bring cold water to a boil in maybe 3 minutes, which is okay with me.

If electric kettles are rare in the States then I think it's because of a cultural difference, not because of the mains voltage. Sure it would be convenient if kettles boiled faster, but I don't think it makes that much of a difference.

Sorry for being thick, but why is that?

Simply a question of available power. Typical British kettles use 3kW (comfortably doable with 240V@13A); under US power (110V@15A) you can only manage about half that, which means waiting twice as long for your kettle to boil.

(American here) I recently upgraded from a 1kW to a 1.75kW kettle and thought it was a huge improvement. It does trip the circuit breaker if I try to run the toaster at the same time as the kettle though.

Oh, I thought US circuits would be spec'ed at higher amperages to make up for the lower voltage. How does that work for high power appliances then? I have a 10kW induction stove, how could you ever get that kind of power from an installation running at 110V?

Stoves, ovens and so on are usually on a different power line from your ordinary socket.

They often run on 220v too.