He mentioned that it's not due to voltage but rather low current circuits. A 15 amp circuit translates to around 1,800 watts in the US and if you derate it to 80% of that like the NEC requires a continuous load you'd have around 1,440 watts available.

His argument is that appliance manufacturers are trying to simplify their lineup by making models that would work in homes without a dedicated circuit (15 or 20 amp). Although I can't think of a better argument that still doesn't quite sound right to me. The NEC has required dedicated circuits for dishwashers for quite a while now and IIRC that requirement has been for a 20 amp circuit for a few decades. Even though you typically only see 15 amp receptacles, kitchens have required 20 amp circuits for somewhere north of forty years.

I think a lot of his video is simply based on testing with crappy Whirlpool and AEG dishwashers. There's a reason why Bosch (and these days LG) dishwashers are pretty much universally recommended.

It's the same issue, if you have a higher voltage then you can get more power without increasing current.

For example in Australia a standard house circuit is 10 Amps, but because it's at 240V we can get 2400 Watts (realistically more like 2300) out of a _standard_ wall outlet that is in every room of your house.