They should have a coin-flipping algorithm running at the same time - I bet they would get similar results.
A coin flipper gets you `50% wins, sure.
e.g.
http://www.rpscontest.com/entry/724002But note that the winner gets ~85% wins, not a trivial lead. In an universe of coin-flippers there'd be no way of doing better but the reality is that people do try and win. And that means they try and use "strategies" less random than coin-flipping which implies one can try and beat them at it.
The other problem is that human opponents are notoriously bad coin flippers. No matter how hard a person tries to be random patterns creep in pretty quickly; so the algorithmic advantage lies in trying to exploit these subliminal patterns. (Only against human opponents, of course)