I recall in my great grandparents old terrace house, the kitchen was set behind the neighbors fireplace. The only rational place for the fridge stand effectively copped 50-80 degrees from the neighbors fire, just radiating from the brick. This lead to the fridge running constantly and having an extremely short lifespan (and sometimes not functioning at all)
That said because it was old everything was air dried.
They have of course been retrofitted with electricity and plumbing and gas and modern insulation (usually), but exactly what you get depends on how recently it's been renovated. And "mid 20th century" is a very common answer.
Also in the USA you see gas-fired tumble dryers, which you never see in the UK, probably due to 240V all round.
And a fair chunk of that is the summer holiday season, when a lot of people won't be home anyway.
It is possible to mis-design houses and apartments to need it more than that (extreme sun traps essentially); schools/offices and public transport are a different case because of the number of human bodies in a small space.
But our homes need A/C so rarely that it's not worth it, same as most people don't have winter tyres or snow chains, or even know how to fit them. Materially significant amounts of snow for a few days one winter in three, unless you live in Scotland or the Pennines.
As a government, it's probably a good move to encourage installation of AC in your citizens homes even if it only gets used a couple of days a year simply for the productivity benefits.
Unfortunately, current UK policies on Heat Pumps specifically discourage installation of AC (you become ineligible for various grants if your heat pump system has a valve to allow use as an AC system).
Many people forget that London (UK) has about the same latitude as Vancouver (Canada).
Different story for badly built apartments, though. We used to live in a 1950s apartment, top floor with a flat roof. It reached 38C inside, when outside was 36C, and then wouldn't cool down at all during the night. It was unbearable, and we moved out!
Not much help if you buy an existing place whose builders didn't take hot summers into account though!
My 20 year old drier uses about twice amount of kwh as my 7 year old dishwasher (on actual clean mode, not "eco: everything is still dirty and you should do it by hand mode"). I also use it far less, so on average they are about the same.
So you have 70m² of wall, 49m² of roof and floor. Total 24.6 W/K. So, with the average UK electricity consumption (300 watts), plus the body heat of 3 people (300 watts) you have 600 watts of heating, which should keep that building 25 deg C above the outdoor temperature.
The UK in winter normally averages about 5C, so you'd have an indoor temperature of 30C - plenty toasty.
Obviously many buildings don't meet the required standards, people aren't home all day, there are air leaks, etc. But, for most buildings, heating is still not required most of the time.
Yes, it's small, but new houses are mostly very small because they try to be 'affordable'.
Most people with lots of money buy an older house which is bigger, sometimes knocking down and rebuilding the same house if you want to modernize (in many areas you have to rebuild something the same size, shape and appearance).
UK housing is mostly quite old - an average age of 50 years or so. Modern insulation requirements only became law in the last 20 years. Most houses aren't particularly well insulated - and most houses haven't had much retrofit work done. The UK is really far behind most of Northern Europe in this regard.
I think the rest of your reasons are valid. Average floor area is probably half that of a US house. Domestic air conditioning is almost unheard of. Almost everyone heats with natural gas.
Heating is a huge part of energy demand - around 25% of UK total energy goes into space heating - so if you're not doing that via electricity then average energy consumption per house will be much lower.
Electricity cost is currently running at about 28p/KWh. I presume that's a lot more than the US. Electric heating is indeed rarer because gas is about 1/3 of the cost.
I'm thinking your points about air conditioning is likely the major difference combined with the average US home being larger so more space to air-con. Few UK homes have air conditioners (offices do) as it doesn't usually get hot enough. Although this has started to change in the last few years and I'm seeing them occasionally popping up now on neighbours houses. I wouldn't have needed one this year at all so far. Last year, maybe for one week. I was thinking about it but by the time you've looked into organising something the heat has gone and you forget about it until next year. There is a push to move to heat pump heating instead of gas and those units often can do air-con as a byproduct so that may be a driver for change.
Tumble driers are easily available and definitely widespread in the UK. The lack of tumbler driers is a bizarre myth I see again and again on lists of differences between the US and UK. I have no idea how the authors of these lists come to this conclusion. The only idea I have is maybe people from the US who come to the UK rent a furnished house and the landlord cheaps out and decides not to supply one. I do have one and it runs to about 2KWh a load maybe? I don't think that would explain the difference in any case.