There seem to be two modes. First, it seems everyone hates it there and management is terrible and people get fired with no severance all the time. The other mode is aggressive recruiting. Here's an actual interaction I had:
Me: I'm torn between doing something new and staying where I'm at.
Random Uber employee: Hey, you should join Uber. Hit me up and I'll refer you.
Me: I can assure you I'm not interested.
Random Uber employee: Wuss...