[threeseed]

It would make sense to use all three.

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.

[liability]

I suspect that optical will also supplement LIDAR in cases where very precise angular resolution is needed, such as human gesture and posture recognition (which is necessary if only because sometimes humans direct traffic, but also for things like profiling pedestrians to anticipate which is likely to jump into the road without looking.) Being able to detect which way a human head is facing will at the very least be necessary, and while you might be able to read faces with LIDAR from a distance, my gut says that optical will give you better data for that.