Optical cameras alone have issues as well that can’t be handled though. It’s the combination of the two along with other things like ultrasonic sensors that makes them safe. More sensors in general are better because they reduce the computational burden and provide redundancy - even if that redundancy is to safely stop.

Cost is certainly an issue, but on $40k+ vehicles it’s cheap enough for other EV makes to include it in the cost. Volvo for instance is using Luminars version at a cost of about $500 (https://www.wired.com/story/sleeker-lidar-moves-volvo-closer-selling-self-driving-car/).

Image processing is expensive even with dedicated hardware and LiDAR provides enough extra information to avoid needing to make make certain calculations off of images alone (like deltas between image series to calculate distance). Those calculations are further amplified by conditions where images alone don’t provide enough information - similar to how there are conditions where the LiDAR data alone wouldn’t be sufficient.