In America or in Japan? I know for a fact if you are doing a new build or renovation in America your choice of involvement is entirely up to you. Some people pick out specific shower heads and toilets and tile (even on a $250,000 renovation or million dollar new build). Others let professionals pick and choose what they want.
There is an entire industry of show rooms for high end bathrooms and kitchens with salesmen to help you pick out the right bath tub or dishwasher.
There is an entire industry of show rooms for high end bathrooms and kitchens with salesmen to help you pick out the right bath tub or dishwasher.