I’m pretty surprised they haven’t been doing that for years already tbh.
Who said they did not? It's probably not public, that's all.
Marketing lead-generation and sales conversion is what every company does with their customer list eventually (sign of a failing business model.) Whether it is internal revenue generation, or a 3rd party... this is what most large web companies trade with Marketers.
I would be more surprised if they kept peoples privacy, as even your credit card company sells the purchase data. =3
That was my thought too. "Starts"?? I assumed they had been selling aggregated data about user trips the whole time.