[jpalomaki]

Might have something to do with the various eco- and energy efficiency labels [1]. I think they show absolute values for water and energy use, but wash efficiency is rated with letters (and the scale is probably set so that most get the A rating). This might create an incentive to try to push those figure down which need to be shown and just make the machine take more time. If you have already reached the maximum rating for washing quality, there may not be point to improve that at the expense of the other figures.

Most of the washing machine purchasing decisions must be based on the marketing fluff. I don't think there are many publications even on EU level which run and publish comprehensive tests for these machines. Without such objective tests, it is pretty much impossible to base the purchasing decision on hard facts (except those mandated to be reported by EU).

I remember reading that some washing machines actually did not even obey the request to use high temperatures, because the manufacturer had noticed that they can match the EU target for wash efficiency also with lower temperatures. Can't find any reference for this, so take this with a grain of salt.

[1] http://www.topten.eu/uploads/File/130904_Topten_recommendati...