Others use both. LiDAR for walls, cameras for object identification below the LiDAR plane, directly in front of the robot. That’s how the fancy ones avoid socks or cables or other small things.
https://bdtechtalks.com/2021/06/28/tesla-computer-vision-aut...
Everyone else uses LIDAR in some form. Tesla's cameras can and have been fooled on many occasions.
https://www.theverge.com/2024/5/7/24151497/tesla-lidar-lumin...
If the algorithms are fed with incorrect data, they will produce incorrect results - such as driving full-speed into a parked, white colored, semi-truck.
I'll let you stew on that one for a minute...
Then that means the vision processing isn't far along yet to be viable for a car. There is no fundamental reason why it couldn't work though. With either stereoscopic vision or more temporal processing you could obviously detect when things are only painted on a wall surface, with both there really is no excuse to still fail except limited processing power.
That's a compelling use case for me but considering how many of these vacuums have had privacy issues, I stuck with Lidar (people cast aspersions on the Chinese companies but US manufacturers have track records that don't inspire confidence either - just ask the Roomba employees who got their naked pics leaked online)
I have a pet (cat) that unfortunately poops just outside her box most of the time, despite a lot of different ideas and approaches with the help of our vet. She's old and has lower back pain issues. It ends up on a litter mat or the wooden floor, so it's not that hard to clean up.
If I had a housemate that pooped inside not in the toilet, they would need to be even less able to manage their shit, so to speak, and more loved than our cat, or they would be out of here very fast.
Ceilings tend to be less cluttered than floors so it is easier to figure out the shapes of rooms and their relationships by looking at the ceiling than by looking at the floor.