I’d be interested in seeing the same figures, but for a pair of trousers washed at 30. Presumably, trousers require much more energy to make, but don’t use any more to wash (though they would be a greater percentage of the load. Actually, I wonder if their figures assume that the pants are being washed on their own!) so the graph would be more in favour of washing.
Agree on there being no point washing trousers that often though (my current pair of Howies troos have been worn since Saturday). And on there not being a need for another Howies bashing thread just yet.