I don't Uber (and have only used Lyft once), so maybe they already do this or are planning to.
Not to mention they have valuable information about you on how sensitive you are to price changes, who you interact with (sharing rides), what places you frequent (bars, gyms, churches, etc), places you travel and on what season. It's a goldmine and more by cross-referencing with other data sets. They can even know when you are sick if you get an Uber to the doctor or if you are friendly or not (drivers also review you) and how strict you are with other people (your reviews of drivers). It's all about the meta-data.
And again, they only have that comprehensive level of data for heavy users. Lots of people only use Uber when they're going to the airport, as others said, or maybe when they plan on drinking.
I use it when I'm running late or public transit is messed up so it's very skewed data for me.
There's also a real risk that Congress or the states could ban them from selling that data.