Comment by latexr

> That's the same situation here.

There is a monumental difference between counting how many cyclists use an intersection and recording the license plates of cars.

If the former, you don’t store any personal information, all you know is how many pass by. You don’t even know if they were different people, 10 of the 50 cyclists you saw could’ve been the same person going in circles.

In the latter, you know which vehicles went by, and when. Even if you don’t record the time you saw them, from the dates of the study you can narrow it down considerably. Those can be mapped to specific people.