I have the feeling Google never had a real plan behind this research project. Tesla's plan is clear. Uber's plan is clear. What is / was Google's plan?
Why can't it be the similar to the Uber or Tesla plan? Just because Alphabet make the bulk of their revenue from sticking ads in front of eyeballs doesn't mean that's how they have to continue making money.
Prevent people from being required to watch the traffic, thus giving them more time to use their phone/tablet, thus show them more ads.
But actually I believe the thing that started the project was more like "let's try to do it" just the same way they started their search engine ... for the first years they didn't have a business plan there either.
https://en.wikipedia.org/wiki/DARPA_Grand_Challenge
I have the feeling Google never had a real plan behind this research project. Tesla's plan is clear. Uber's plan is clear. What is / was Google's plan?