Message from PReDS:
In Heroes, people generally play relying on the opponent's honesty. What you described is much easier to check than map hacking or, for a simpler example, a rush with red units on a small map.
And to prevent units from dying in an empty town, leave a single unit of level 1 there.
Therefore, the goal should be to eliminate the very possibility of dishonesty.
Half the world plays Heroes, and the claim that they play relying on honesty is unsubstantiated, as no one can know what's in everyone's mind. You can trust or distrust, but you can't be certain without proof.
