This is exactly how Google maps knows traffic conditions.

Is there an on-by-default "use my location data to push dubious pro-corporate agenda under the guise of academic research" checkbox in google maps ?

And Google provides histograms of how busy a store is at each hour of the day.

Of course, the least busy hours are always my work hours.

It's not exactly the same. You're using a google product while they harvest your data, which is different than a company or researcher buying that data from a broker. Though I suppose Google could also be buying information separately.

Safegraph, for anyone interested. https://www.safegraph.com/privacy-policy

> To avoid having your device’s mobile advertising identifiers (and location data associated with it) used for our services, [...] iOS mobile devices, Settings -> Privacy -> Advertising -> Limit Ad Tracking: On [...] For Android mobile devices: Google Settings -> Ads -> Opt Out of Interest-Based Ads or Ads Personalization

More complete path (for Android 10 at least):

Google Settings -> Privacy -> Advanced -> Ads -> Opt out of Ads Personalization

It's surprising how many companies out there are selling similar datasets.

Who else did you have in mind?

What’s unethical about it?

The fact that the people whose location is in this data set almost certainly never gave their informed consent for it to be used this way, much less fused with other information about them such as race, income etc.