As of 5 or so years ago, the lidar used for this on the research side of things started at US$10k per unit (and for "surveying" you can do ok with one-on-top but for navigating you need something smaller and not sticking out of the roof, so then the car itself is a blind spot so you want 2x or 4x units.)
As a robot developer, I was really hoping that high-volume self-driving would lead to lidar mass production (and thus price drops), and there was one promising non-mechanical lidar that was aiming for $1000/unit for an self-driving-grade sensor, but I've lost track of it...
They are cheap, but range and resolution are terrible. More comparable are the radar units for the "car in your blindspot" lights in mirrors (not really comparable to lidar at all, just vastly better than sonar.) Tesla dropped those too, with a claim that they were a lot flakier than their optical system (which I don't dispute - the material the published about it was pretty convincing - though mostly it gave the impression that Tesla's radar implementation was terrible, and that optical modeling beating it wasn't as impressive as it might sound.)
Even if we take this at face value, and assume that the camera is better, the implementation is horrible. Don’t force the driver to look at the screen in the middle, put red lights in the mirrors instead.
But as usual Tesla likes to be different for the shake of being different even if this makes the car worse
