The monorail video is jaw-dropping.Yes. Pause the video and look at the car's screen. There's no indication on screen of the columns. A car on the other side of the row of columns is recognized, but not the columns. It's clear that Tesla has a special-purpose recognizer for "car".
The columns are a solid obstacle almost impinging into the road, one that doesn't look like a car. That's the standard Tesla fail. Most high-speed Tesla autopilot collisions have involved something that sticks out into a lane - fire truck, street sweeper, construction barrier - but didn't look like the rear end of a car.
As I've been saying for years now, the first job is to determine that the road ahead is flat enough to drive on. Then decide where you want to drive. I did the DARPA Grand Challenge 16 years ago, which was off-road, so that was the first problem to solve. Tesla has lane-following and smart cruise control, like other automakers, to which they've added some hacks to create the illusion of self-driving. But they just don't have the "verify road ahead is flat" technology.
Waymo does, and gets into far less trouble.
There's no fundamental reason LIDAR units have to be expensive. There are several approaches to flash/solid state LIDAR which could become cheap. They require custom ICs with unusual processes (InGaAs) that are very expensive when you make 10 of them, and not so bad at quantity 10,000,000. The mechanically scanned LIDAR units are now smaller and less expensive.