The problem is just that the board can usually claim they did not know, and that they have deep pockets to afford good attorneys. To get around the first thing, you have strict liability laws.

Strict liability laws, though, are how you end up with the situation where barkeepers are criminally liable for selling alcohol to underage people, even if they could not have known the buyer was underage (and that's about the only instance of strict liability in criminal law). I personally find this very unjust and would rather that strict liability was not part of criminal law.