In my city, there doesn't seem to be any two-bed one-bath apartments, if you want two bedrooms, your only choice is to also have two bathrooms. The majority of two-bedroom floorplans I've found online also reflects this. Is there a reason why having one bathroom for two bedrooms is so unpopular? I can't imagine a family that occupies two bedrooms have that many instances of two people needing the bathroom at the exact same time, other than maybe in the morning, but even then it wouldn't be the case for every family. Wouldn't it make more sense at least for some people to use the space that would have been for a second bathroom as a storage room or a small study? That space could also just not exist and result in a somewhat smaller and cheaper apartment.
This is from the perspective of US and Canadian apartments, are two-bed one-bath apartments more common in other parts of the world? If not, why? I definitely remember our apartment in China had three bedrooms and one bathroom, but it's an old building and I don't know if new apartments are still built like that over there.