It probably gets real interesting when they're trying to distinguish between various modes of transit, such as a city bus, an Uber/Lyft/taxi, and a private vehicle not participating in rideshares. Of those examples, the latter would suggest the highest degree of association.
Pure speculation, but I wouldn't doubt they take a peek at ridesharing data for co-traveler inference purposes. Knowing if a rideshare driver is on or off the clock would be incredibly valuable information in that context.
[0] https://www.washingtonpost.com/apps/g/page/world/how-the-nsa...
I was doing all of this five years ago, the capability has been around for a while.
The NSA only recruits in the USA. It's a fraction of the talent pool of the planet.