I am pretty sure I've seen videos of commercial robots power washing public bathrooms. Probably not a solution for normal bathrooms with wood furniture and fabric items but it is definitely possible today.
In Scandinavia you get a lot of ceramics, such that a shower+toilet can effectively be the "water room". I'd think that ceramic tiles can be tackled by a 'bot. A flat, unyielding surface, usually with a light color that provides high contrast with gunk. Bring on the ScrubBots(TM).
As a Norwegian in the UK, I've spent 24 years despairing over - and annoying anyone within earshot by talking about - the lack of proper wetrooms in most UK houses. In fact, a lot of British builders seem to think making floors waterproof requires dark magic.
It's slowly getting better, but it's still confusing enough of them.
Reminds me, I read once about a guy who made a plastic-lined living room with plastic furniture and a drain in the floor. Post-party cleanup was just pointing a hose at it all.
