You could wire your house for 12, 24 or 48V DC tomorrow and some off-grid dwellers have done just that. But since inverters have become cheap enough such installations are becoming more and more rare. The only place where you still see that is in cars, trucks and vessels.
And if you thought cooking water in a camper on an inverter is tricky wait until you start running things like washing machines and other large appliances off low voltage DC. You'll be using massive cables the cost of which will outweigh any savings.
In all likely not worth the trouble. When I moved to Canada I gave away most of my power tools for that reason and when I moved back I had to do that all over again.
If you ever have to do it again, you can probably get a transformer rated high enough for power-tools for cheaper than replacing all of your power tools.
I think the answer to your question is that it mostly doesn't matter for personal mug size quantities of hot water and if it does matter to you there are readily available competing options such as dedicated taps for your kitchen sink.
Perhaps the biggest reason is that a traditional kettle on any half decent electric range will match if not exceed the power output of any imported electric kettle. Many even go well beyond that with one burner marked "quick boil" or similar.
I’m surprised that American exceptionalism can tolerate half powered sockets.
How expensive would a proper AC->DC->AC brick for that power level be?
A pure sinewave inverter for that kind of power is maybe 600 to 1000 bucks or so, then you'd still need the other side and maybe a smallish battery in the middle t stabilize the whole thing. Or you could use one of those single phase inverters they use for motors.
No one in the USA drinks hat tea. The choices (and it tends to be regionally-based) is sweet or unsweet tea. No need to boil a kettle quickly for that.
There are dozens of us.
Perplexingly I was traveling in one of the iced tea regions of the country in need of a cup of hot tea, and they had no way to make it. Like, you have a commercial coffee maker and hot cups, the coffee maker has a hot(ish) water tap. All you need is a $4 box of teabags that’ll last until the heat death of the universe. Nope.
Still though, I don't seem to see most of those people seriously clamoring for the electric kettle to go a bit faster. The cost for the wiring difference and dealing with odd imported kettles just isn't worth it generally.
... Unless you're buying it pre-made, does this not still start with making hot tea the regular way? Or what exactly are you doing with the tea bags and loose tea from the supermarket?
I've heard of Americans getting EU plugs for things like this, but it's extremely uncommon. The simple answer is: Americans just don't drink tea very much, and the ones who do aren't going to go to this much trouble and expense just to be able to boil water for their tea twice as quickly.
It would be relatively easy for the US to go to 240V: swap out single-pole breakers for double-pole, and change your NEMA 5 plugs for NEMA 6.
For a transition period you could easily have 240V and 120V plugs right next to each other (because of split phase you can 'splice in' 120V easily: just run cable like you would for a NEMA 14 plug: L1/L2/N/G).
What would be the real challenge would be going from 50 to 60Hz.
Other way around, no? The US is already 60Hz.
Edit: I mostly remember this because the SNES games I used to buy in the US and brought back to Europe ran noticeably slower.
I can watch 1080p video on YouTube and it runs in an up-to-date web browser using less than 50% CPU on 12-year-old hardware with 8GB of RAM and a graphics card that was a budget option at the time (my searches indicate it draws at most 80W, though it expects a 500W PSU for some reason).
