They haven't been relying solely on "fancy imaging/neural algo" - every self-driving car since the DARPA challenge has used LIDAR, and a good chunk of the self-driving R&D funding has gone into making those cheaper. The LIDAR they're bragging about in this blog post is them adding four more sensors to the car for short range, on top of the one they already had on top.

mm-wave radar gives them better sensing for long ranges and in bad weather, but isn't a fundamental change in approach from their already-sensor-heavy tech.