This strikes me as a skunworks project to investigate a technology that could be used for autonomous vehicles someday, as well as score some points with Sundar and the Alphabet board who've decreed the company is all-in on Gemini.

Production Waymos use a mix of machine-learning and computer vision (particularly on the perception side) and conventional algorithmic planning. They're not E2E machine-learning at all, they use it as a tool when appropriate. I know because I have a number of friends that have gone to work for Waymo, and some that did compiler/build infrastructure for the cars, and I've browsed through their internal Alphabet job postings as well.