They didn’t. They went to ngrok and asked for all the data at the point of signup. They then looked to find the any of that data at the second site. In this case they had two identical data points - the GDID and the IP address.
What people generally want is time, and then if you have time you obviously need to spend it somewhere. If not work or home, then literally a third space.
>t’s hard to answer and I think partially for better or worse why markets are often a useful tool to o help figure it out
The point of the article is that the markets are blind to this sort of social good.