I've lived in 17th Century buildings in the UK that have all for washing machines - I doubt the apartments there had washing machines in mind when they were built :)
You guys also put your washing machine in the kitchen. In the US the washing machine goes in a different room, which means you have to run a lot more plumbing. Combination machines are also extremely rare, and people don't really air dry clothes much, so you need space for both a washer and dryer.
Plus a unit with an in-unit washer and dryer generally costs more than a similarly sized unit, and part of that space is taken up by a washer/dryer.
Plus a unit with an in-unit washer and dryer generally costs more than a similarly sized unit, and part of that space is taken up by a washer/dryer.