What makes you think it doesn't? All those cameras, the expensive chips and cooling for them, and redundancy for all the systems don't come free.
(FWIW, the business story for Waymo has never been about its hardware making its way to consumers. It's always been about whether Waymo continues to run its own taxi service or leases out hardware and operations to other taxi businesses).
It's maybe $1.5K of BoM total for the chip, memory, and cameras.
Where are you seeing this? The estimates I've seen all land around $1K.
The 5 millimeter-wave radars and 12 ultrasonic sensors are $100-150. LiDAR is $150-200. The 12 cameras, control unit, and 300 TOPs of computing is $150-200. This computing is comparable to what Tesla puts on their consumer cars, and the sensors suite is much more extensive. (The current robotaxis have about the same computing power as the consumer cars but a lot more RAM).