There were many factually correct, and even historically interesting responses. But not a single response answered the question.
Are they, though? With modern appliances, power requirements are going up and 110V is struggling to keep up. One example would be an induction hob.
I know that technically US homes can access 230V but they aren't wired for that, probably 99% are wired just for 110V except for maybe a few special lines.
The reason for gas in the US is because people like it. It's been seen as upscale for decades to have a gas cooktop. It also helps that gas water heaters don't require electricity and work in an outage. Our residential natural gas distribution network is extensive and reliable, and it's pretty straightforward to use the same appliances on propane for people out in the sticks.
Things like lightbulbs and TVs and computers and refrigerators are using less power than ever before.
Of course, if people are buying electric cars or replacing gas furnaces with electric heat pumps, then you're right on that side of things.
Are they, though?
Lightbulbs, sure, we won with LEDs.
But TVs, especially the huge, high brightness ones we have nowadays? And with the extra computing needed?
Computers, same, I only see power usage going up. I mean PCs, we're not comparing things with mainframes here :-)
Refrigerators: are they really more efficient?
Now add: heat pump, induction stove, electric oven, more powerful AC, humidifiers/dehumidifiers, etc.
And compared to the age of the Pentium 4 with its 100W+ TDP, laptops now outsell desktop computers by a long way.
(I would agree that things like high-end gaming GPUs are using more power than ever before - but they're also a much smaller % of sales than ever before)
According to the internet a CRT TV used to use about 100W, while a big LCD TV can use more.
Regarding desktops, don't forget that these days we have many more electronic device in a home. Smart speakers, home media devices, consoles, etc, etc. Electronics probably use, in aggregate 5-10x what the old family PC used to use, I'd imagine.
To change my gas stove/oven back to 240v induction would be a 15 foot run of romex, a new outlet, and probably an updated circuit breaker. Possible for a DIYer to do.
Older houses might have a dedicated 240 plug for the dryer and the stove if they're not natural gass, but for everything else there are plenty of homes full of ungrounded 10 amp 120v circuits.
And yeah, my house is full of 120V circuits, but once again the house has 240V at the panel and could run 240V anywhere in the house if needed. As you pointed out, they probably do have a 240V plug for the dryer, ergo they've got 240V service at the property, so they could wire the kitchen if there's no wiring already. Once again, practically nobody has only 120V service at their home.
US Version: https://www.bosch-home.com/us/productslist/cooking-baking/co...
UK Version: https://www.bosch-home.co.uk/product-list/cooking-baking/hob...
Largely they have the same power output. While the total power available is actually higher for the US version at 12kW versus 11.1 kW for the UK version. That is because the US version needs to be on a 50 amp 240v circuit versus the max 16 amp circuit for the UK version.
Even this Bosch one: https://www.bosch-home.co.uk/product-list/cooking-baking/hob... Which clearly calls out 400v 3 phase has a lower power output at 7.4 kW.
The max output to a single pan/pot typically is going to max out around 3.3-3.7 kW. I don't know the exact reasoning behind that but I assume it might cause issues with cookware if you go much higher than that.
Assuming 120v loads are split reasonably equally between each leg of the 240v phase, the load will mostly be on the 240v circuit because both legs are connected in series. The neutral back to the transformer is only used to carry the difference between the 120v load on each leg of the phase, and also to keep the system grounded.
I guess if you had a panel close to load capacity, as well as a single very high amp 120v device, the transformer could enable some more capacity by ensuring the load was distributed equally between the phases. However at that point a service upgrade would probably be necessary anyway based on the load calculation rules in the code. Also high amp 120v devices are quite rare as far as I know, so I was wondering why you went with this unusual setup.
(from the wiki: https://en.wikipedia.org/wiki/Electrical_wiring_in_the_Unite...)
UK fixed wiring circuits, unlike those found in almost all other countries, make widespread use of ring circuit designs, as well as radial circuit designs often seen in other countries. (This was one of the recommendations of the Electrical Installations Committee, convened in 1942 as part of the Post War Building Studies programme, which in 1944 determined that the ring final circuit offered a more efficient and lower cost method to support a greater number of sockets.[6]) It continues to be the usual wiring method for domestic and light commercial socket and device wiring in the UK. Lighting circuits, which typically have lower power requirements, are usually radially wired, confusingly sometimes called "loop" wiring.
Safety was one significant concern. 230-240V is more likely to stop a person's heart. 220 is available in most US homes for specific cases where it is more practical.
Speaking from experience, I don't think it is uncommon for a person to have been electrically shocked at some point in their lives --- often when they were a child.
Wire insulation deteriorates over time. Rodents like to chew through it. Water can find it's way in through plumbing or roof leaks. Higher voltage is more likely to start a fire in these instances.
The total number of fires of electrical origin in the EU is estimated to be 273,000 per year.
Fire departments responded to an estimated average of 46,700 home fires involving electrical failure or malfunction each year in 2015–2019.
https://www.europeanfiresafetyalliance.org/publications/whit...
https://www.nfpa.org/News-and-Research/Data-research-and-too...
What keeps a kid from sticking something metal into it?
UK plugs and sockets are really, really, really safe. Except to stand on.
You can try pushing with something like a screwdriver (to test for live) and it's hard to pivot the plate (feels like it needs both pins to pivot), and a non round tool snags on the plastic cover plate.
On the other end, in India I saw a power strip that would accept EU, UK, or US plugs. I took one look and refused to get close, but someone else plugged my laptop in and it worked. (everything got 240 volts, which my laptop power supply was fine with)