Why autonomous miles matter

When a robotaxi company claims it is safer than human drivers, the number underneath that claim is miles — specifically, cumulative rider-only miles driven with no human in control. The more real driverless miles a system has logged, the more rare, dangerous and strange situations it has actually encountered and handled.

That is why miles are the denominator under every safety statistic. A low crash rate over a few thousand miles means little; the same rate over 100 million-plus miles, as Waymo has now driven, is a serious dataset.

Miles are not a perfect measure — where and how they were driven matters, and comparisons across companies need care — but they are the closest thing the field has to a shared yardstick for real-world experience. The tracker records cumulative rider-only miles so that experience base is visible over time, separate from marketing claims about safety.