GoKawiilA human cleaner has a really big advantage over a vacuum: it can move things out of the way. That doesn't seem like a huge problem, but the vast majority of robot vacuums lack arms. It can't just move a chair or get a hoover nozzle into a tight spot to clean up dust. There's also the unknowns to think about that it won't have mapped on its route, like toys, charging cables left trailing across the floor or even pet messes that can be spread around the house.
That's not to say that robot vacuums can't overcome some of the issues. By design, even basic robot vacuum cleaners will change direction or move aside if they encounter an obstacle, rather than just following their pre-planned route. The cheapest models will use bump sensors, so it'll need to physically collide with something. That can leave it going over the same patch again and again when it runs into a barrier. The best robot vacuum cleaners may use infrared sensors to try and bypass this, with the most expensive relying on LiDAR sensors and AI cameras to work out its surroundings better.
Yes, more expensive models will have more freedom to navigate as they can identify more problems to work around. That said, even the most complex models can't deal with some obstacles, at least very well. Loose cables are a good example: they can wrap around brushes or wheels and stop the vacuum in its tracks before it completes a run. Socks are another problem that can get sucked in, as can lightweight rugs, unless you have a model like the Roborock Saros Z70 that can move things out of the way. While robot vacuum cleaners are more independent, you're still going to need to check your floors beforehand, just to make sure that it won't run into a problem that it can't ride around.