alt Hacker Newsi have robot running daily. it will never pick up 100% of everything. because if it would have picked up 100% there would be no need in mopping.
when i did robot shopping year ago, based on reviews and feedback it (vacuum before mopping) doesn't always work and the more polished your floor is, the worst the outcome
No, mopping is not for dust, but rather for sweaty/greasy/sticky matter that accumulates and can't be recovered by vacuuming. This is why proper cleaning is vacuuming + mopping, and it was like this before the invention of the cleaning robot.
You can also mix a non-foaming detergent with the distilled water to have an even more thorough cleaning (or just ask the robot to pass more than once). Robot mops are typically rougher to compensate for the lack of detergent, though.
It's the same for professional car cleaning - it's done with distilled water. If what you said was true, it would be impossible to clean cars as they are much more polished than tiles.