It should be noted that in many places in the US that hanging clothes outside is either not allowed, or impractical. Also I've had some really bad nights (baby) where I needed to wash and dry all my bedding twice over, so having a, rather fast, dryer was nice.
Seriously though, if you need to wash a large comforter, what do you do? I haven't seen a front loader large enough to fit a proper comforter in. Something like http://canyon-sports.com/wp-content/uploads/2019/02/91YEVCAn...
In America, you can buy top loaders or front loaders. Front loaders are popular in condos and apartments because you can stack them with a dryer.
Regarding the sizing again, I’ve never had a problem. I’ve also never heard of anybody washing a comforter (although I don’t call it a comforter so maybe I’m misunderstanding what you mean). A comforter (or duvet) has a cover on it and you wash the cover.
If the machine is stuffed full this doesn't work, the water gets caught in some fold of the clothing and you end up with 1 damp spot and an otherwise dry duvet.
I Air BnB'd my way around the UK, the washing machines in the places I stayed were generally tiny, like smaller than anything I've even seen in the US, but that could've just been an artifact of me staying in Air BnBs.
They all did share the trait of getting the clothing seemingly scorching hot to dry it though. :/
American top loading machines are generally huge. Now days they have sensors to detect how much water they really need to use, so they aren't going through LMAOWTFBBQ gallons of water like they did when I was a kid.