For all Tesla's problems, the automation-via-cameras solution is the one I find myself having the least problems with: using a single, obvious input (to humans), you don't wind up in a situation where you can have multiple differently-capable systems disagreeing on what they're seeing.
I can only suggest you think harder about the 'all cameras' approach. Imagine say a snowstorm. Hail. Rain. Ice sheets. Sun in your 'eyes'. Cameras, basically, suck. Elon's game is to use suck-tech and make it un-suck with computons. Bad Choice.
The reason is simple: cost. The goal isn't to build a proof-of-concept safe AV, it's to build one that meets the safety bar _and_ is as cost-effective as possible, in a reasonable timeframe.
I happen to agree with the target-then-scale approach, but I also agree with Kyle that it's not a given that this is approach is definitely superior to the one that launches everywhere and tries to improve functionality.
By using all (or almost all) available Active and Passive sensing technologies, fused with geofencing and operating at 'low-ish' speeds -- surely must be the fastest way to achieve 100% accident-proof self-driving vehicles that operate on ordinary city streets. Congratulations, Cruise. Keep up the Good Work.