There is no causal claim in my post. The second sentence exists for emphasis.
That said, I'll now surmise a chain of causality based my experience with Sidecar. I found nearly all drivers asked for above-market rates, thus failed to attract customers and ultimately quit the service. I spent the summer of 2014 commuting in various U.S. cities exclusively via rideshare apps. I'd compare Uber, Lyft, and Sidecar, and always pick the cheapest option. I took over 100 trips, of which exactly 2 were through Sidecar.