it seems that women in US rather look for type of dress, like 'evening dress' and then drill down other attributes.
That would match my wife and daughter's behavior, I think.
Is it possibly the case that shops in US are so well stocked, that they have all the sizes, all the time?
Actual stores divide things into large sections: "teen", "petite", "normal", "plus sizes." Online you find whole stores specializing in particular size ranges, but in general the process seems to be "find a dress you like and then curse because it doesn't come in your size." Are there actually UK stores that sort FIRST by size?