Do robot window cleaners actually work?

Across the reviewers we read, the consensus is that they work well as a maintenance tool but not as a full replacement for a human cleaner. Specialist subreddit threads repeatedly describe results around 90% as good as hand-cleaning, with the robot often missing the last 1-2mm at the very edge and occasionally needing a touch-up where it stops. They shine on large or tall windows where reaching by hand is impractical.