It is a matter of point of view, how many waymo car have been sold to customers ? how many waymo cars are out of the waymo car factories every months ?
There are several things to tackle and different approaches to things, the DARPA grand challenge is the practical one and waymo did not took part in any edition AFAIK.
From Waymo's wiki page: "Google's self driving car project was formerly led by Sebastian Thrun (...). Thrun's team at Stanford created the robotic vehicle Stanley which won the 2005 DARPA Grand Challenge and its US$2 million prize from the United States Department of Defense. The team developing the system consisted of 15 engineers working for Google, including Chris Urmson, Mike Montemerlo, and Anthony Levandowski who had worked on the DARPA Grand and Urban Challenges."
There are several things to tackle and different approaches to things, the DARPA grand challenge is the practical one and waymo did not took part in any edition AFAIK.