I seem to remember it's just assumed that the washing machine is filled up to x % of capactiy on average, and that this is also at least partially to blame for

I seem to remember it's just assumed that the washing machine is filled up to x % of capactiy on average, and that this is also at least partially to blame for the disappearance of smaller washing machines [1] – bigger washing machines are more energy-efficient, assuming they're actually used to capacity. Because assumed usage simply scales with the machine's capacity, manufacturers can simply bump up capacities in order to make their machines appear more efficient, never mind how much people actually fill up those machines in practice. [1] Our old washing machine had a capacity of something like 4 or 5 kg, which was perfectly fine for how we used it, but when we had to replace it a year or two ago, it was hard to find anything smaller than 7 or 8 kg.