> The ground unit cannot hurt the air unit in any way, and the air unit can hurt the ground unit. This relationship is based on innate and immutable differences between the two unit types.
There are some ways in which ground unit can still win the game in this scenario. For example if you can flood the enemy with zerglings and kill his buildings just ignoring the air units slowly picking the zerglins apart.
So, in a way - there are no hard counters either :)
Generally a unit would only be considered a hard counter if it could destroy the other unit in a reasonable amount of time. If a swarm of zerglings can take continuous fire from some air units and still manage to destroy an entire base before being destroyed themselves, then the air units aren't much of a counter...
There are some ways in which ground unit can still win the game in this scenario. For example if you can flood the enemy with zerglings and kill his buildings just ignoring the air units slowly picking the zerglins apart.
So, in a way - there are no hard counters either :)