Open source doesn't fix much. Most ad tracking today happens via well understood open technology, and then adtech companies build profiles server side. Here's something very simple and fully opensourceable that would still provide lots of tracking capability:
* Get lots of sites to put an img tag that references your site, perhaps by paying them a tiny amount per visitor
* When you get a request, assign a cookie if there isn't one. Log the cookie and the referrer.
* Sort your logs by cookie. Each cookie represents someone's browsing history, and the more complete your distribution of pixels is the more complete your view is.
You can opt out of this client side by blocking the requests (adblocker) or by using a browser that blocks 3rd party cookies (ex: Safari) but open source doesn't do much here.
In the parent post's defense, open source would actually allow for looking at exactly what data is sent how. And hold the companies accountable. This would be dead easy, without the need for whistle-blowing, or reverse engineering
At the basic level, you have no idea what the system software is gathering from sensors, like the accelerometer, barometer, GPS, wifi signals, etc, how it is processed, and how often it is sent, and to whom. After you find out how that works, then the next logical step is to ask just what the heck the other side is doing with it.
* Get lots of sites to put an img tag that references your site, perhaps by paying them a tiny amount per visitor
* When you get a request, assign a cookie if there isn't one. Log the cookie and the referrer.
* Sort your logs by cookie. Each cookie represents someone's browsing history, and the more complete your distribution of pixels is the more complete your view is.
You can opt out of this client side by blocking the requests (adblocker) or by using a browser that blocks 3rd party cookies (ex: Safari) but open source doesn't do much here.