I will tell you specifically about the case for a car ride application here in Brasil called 99 Taxi.

The developer approached the taxi drivers on his own, explained to them how talking directly to the clients requesting a transportation was more efficient than waiting for one to stop by their side.

They were willing to try it out.

Also, he taught them something they didn't know about how to quickly use their smartphone browser for something they wanted (not business wise).

That did the trick.