How do they know when these drivers are driving vs. being a passenger? Do they rely on the driver to click a button to indicate that? Or do they just assume tha

How do they know when these drivers are driving vs. being a passenger? Do they rely on the driver to click a button to indicate that? Or do they just assume that anytime a cellphone is going a certain speed, the user is driving? I did not see this addressed in the article and frankly, without knowing this, their data is completely useless. For all we know, they're gathering data on passengers.