These seem meaningfully different than UK's facial recognition vans. The government has to request the footage from Waymo for a specific place/time. I don't think they can put in requests like "analyze all Waymo video data for this particular face and tell me where they were and when". It's much narrower in scope.
It's conceptually pretty similar to cell tower dumps, where they ask for all data from a cell tower during a particular time frame. This was recently ruled unconstitutional (https://www.courtwatch.news/p/judge-rules-blanket-search-of-...), but they used it for like 15 years before that (https://arstechnica.com/tech-policy/2013/08/how-cell-tower-d...). I can imagine blanket car footage dumps working for a similar amount of time.