$1,000 is not a meaningful amount of money to Google. Maybe if, based on the fact the entire fleet uses the same software, it is fined $1,000 per car in their fleet each time an incident occurs?
Bear in mind $1,000 per incident is not enough money to justify paying a software developer to fix it.
If this behavior actually is a prevalent issue, then there will be many fines that add up. If Google doesn't rack up many fines, then this problem is evidently rare.
Well, you can just treat them like they are anybody else. So, $1000 fine plus a point on the license of Waymo. And as suggested by another commenter in the thread, if the cars in the fleet (collectively) accumulate more than 4 points within 12 months, Waymo loses its license. As in, all cars operated by Waymo.
Ticket and require a company lawyer and programmer to show up in traffic court for every infraction and explain current status of self-driving software.