The reason for this seemingly dotty result is that the errors from scientific sampling are easier to quantify (and minimise) than those arising from an imperfect head-count.
Although there are likely several reasons for this, and the sampling size might not qualify this as a statistically significant result, I would offer that if you approach a game with the idea of how to work around the rules of the game in increase your odds of winning while your opponents are simply following the rules, your chances of winning will dramatically improve.