They don't seem beefy to me. I don't see why a small electric motor at 240V would use 5 amps. A 1 hp motor uses about 7. Even my shop type vac has a cord that I'd say is about the size of a pencil.
They are actually the source of a lot of fires. People put them under carpets for example, where they get rubbed, frayed. Or they take a minimal gauge cord and plug 6 things into it. Or they string together several short ones, that aren't in the greatest shape, etc. Plus they are a trip hazard. Plugging a hot plate or similar in on an extension, you could trip on the extension and have a hot pot of water land on you.
I can see that. The 120V one here I used to heat about a liter of water to make coffee or tea. If I need more water than that, I do it on the stove. I agree having a 240V electric kettle would be a very handy thing. I never thought about it until you brought it up. Maybe we can get something started here, put in 240V receptacles for new kitchens. I'd like it.
I've never seen those. Trend now is to more front loaders. There the detergent goes into a reservoir at the top of the machine, but I think it's loaded for each use.