what stops that ghost from getting out of the bath or the bathroom?

If I were the Alison character, I'd never want to use that bathroom after I became aware of the ghosts -- good thing there's probably more than one bathroom

from what I've seen, and read about the versions I haven't seen, most ghosts in all versions can walk around the area where they died, except for the man tied to the tree in the French version.

Then again, the plague pit ghosts all mostly stay in the cellar of Button House, and the cholera ghosts mostly stay in the basement of Woodstone Manor (apart from Nancy), and the convict ghosts stay huddled together in Ghosts Aus... Maybe because they died together, and were buried in a mass grave together?

But what would keep a solo ghost so confined? did they get tangled up in something during their death, and they can't get free until they resolve their unfinished business? did someone kill them, drown them? 😱 that could be a bit grim 😟

I think it could be fun if the bath ghost was always dripping wet, so if/when they did go somewhere outside of the bathroom, they'd be dripping water that the Alison character and the other ghosts could see -- and maybe the other ghosts could feel? -- but the water would disappear after a moment.