I've been told that Waymo (and before that, Google) recorded those traces using employees in the driver's seat, but mostly with the computer making the decision

I've been told that Waymo (and before that, Google) recorded those traces using employees in the driver's seat, but mostly with the computer making the decisions, not the human. But suppose it was collected by a human. In that case, the first time the software is run completely (all sensors, all software, everything run together) is in the final production deployment. Is that better than testing the very same software earlier, in a beta setting which is identical to production except that sensor data is collected for the development process?