A room with the bathroom down the hall is often treated as a relic. It survives because adding plumbing to an existing building is the single most expensive renovation a small lodging can undertake.
Plumbing is vertical and the building is not
Water supply and waste both need runs to a stack, and a stack has to pass through every floor in the same position from the roof to the sewer connection.
Older buildings were not built with those chases, so adding a bathroom to each room means cutting through structure and losing floor area on every level.
The cost lands on a small number of rooms, which is why a six-room inn cannot amortize it the way a two-hundred-room hotel can.
Room size falls when a bathroom is added
Fitting a private bath into an existing room takes a meaningful bite out of it, and in a small room the result is a bed with no space around it.
Historic properties often face preservation limits on moving walls, removing original features or altering window arrangements, which restricts where a bath can go.
Operators then choose between fewer, larger rooms with private baths and more, smaller rooms sharing them, and the arithmetic does not always favor the first.
The ratio determines the experience
What matters to a guest is not whether a bathroom is shared but how many rooms share it, and whether the peak demand hours overlap.
A single bathroom serving two rooms behaves nothing like one serving eight, and the difference shows up entirely between seven and nine in the morning.
Properties that run this format well publish the ratio and often add a separate toilet so the two functions are not competing for one door.
Fixtures shape the layout
Splitting a shared facility into separate toilet, shower and basin rooms multiplies the number of guests it can serve without adding plumbing capacity.
In-room sinks do the same work, removing shaving, brushing and washing from the shared space and leaving it for the functions that genuinely need it.
A room advertised with a private sink and a shared shower is usually the result of exactly that calculation.
What the discount actually reflects
The price gap between shared and private baths in the same property tends to be substantial, because the operator is pricing the inconvenience honestly.
The gap is widest in cities where the alternative is a small chain hotel, and narrowest in places where nearly all older stock is arranged this way.
For a short stay or a solo traveler, the questions worth asking before booking are the ratio, the distance from the room, and whether robes are provided.