There's a company, and this is my favorite example of the sharing economy called Bloblock Car. They can make profits by anything that looks like a problem is actually a profit opportunity. If you could commodify that excess capacity and solve the three transactions cost problem, triangulation, transfer, and trust, you could have hitchhiking. The reviews that are available mean that both the rider and the driver can evaluate each other.
Economist and author Michael Munger of Duke University talks about his book, Tomorrow 3.0, with EconTalk host Russ Roberts. Munger analyzes the rise of companies like Uber and AirBnB as an example of how technology lowers transactions costs. Users and providers can find each other more easily through their smartphones, increasing opportunity. Munger expects these costs to fall elsewhere and predicts an expansion of the sharing economy to a wide array of items in our daily lives.