I’m sure this is a dumb question to anyone with knowledge in this field but is there any reason to not use all three together?
To be specific about waymo (to be clear I work at Google, but don't actually have any special info on this), look at the photo in [0]. The cone thing on top is a lidar, but also has cameras in the larger part under the cone. The spinny thing on the front is also probably a lidar. The fin that looks like an extra mirror on the back, and the two on the front have radar. There's also probably a forward facing radar mounted on the nose somewhere near the grille.
[0]: https://waymo.com/
Sounds like a reasonable trade off. No one needs to own these cars just rent them on demand. Plus some wealthy people in the early adoption curve.
Lidar used for long range. Vision used for things like colour recognition e.g. is a traffic light green/red or is an ambulance sirens on. Radar used for reversing etc where Lidar given its location might not be able to see that close.
No-one is expecting to use experimental $75000 Velodyne units in production.
The number one link if you search "Tesla" on HN is "All Tesla Cars Being Produced Now Have Full Self-Driving Hardware." It's been an extraordinarily effective marketing gimmick.
Obviously not the same specs as Waymo's LIDAR but at least, it proves that it doesn't have to be that expensive.
A Lidar is a significant part of that.
If $40k Tesla can do as well as $40k car + $75k of sensors (including lidar) it's economical game over. Tesla wins by a wide margin.
The $75k will drop in time, but the battle will likely happen before the price of lidars drop significantly enough.
There would probably be room for both these models (direct sales that capture much of the self-driving value and leasing), but regardless there are obviously strong incentives for a 5- or 6-figure reduction in costs.