My wife (mid-20s) and her friends were going to take one for the first time after I told them about it as they were headed to Chicago for the weekend. They all got scared and took a cab instead because they had never heard of Uber and didn't trust it. Nothing I could say would convince them otherwise, they need to hear about it from other sources to think it's legit.

People just don't know about Uber. They're not recognizable enough (no advertising).