"And, as you said, there isn't any mandatory minimum penalty if government fails to do its part. This is what needs to be fixed."
Further, the two forms of ID required are (1) Social Security card (2) Picture ID (Drivers License, State ID, or Passport). I think that is it. (1) can be easily forged. (2) can be forged easily enough - or obtained legally from a government such as California.
On top of this, employers can hardly be expected to be experts at detecting well-made fake or duplicate IDs. If someone looks underage, you BETTER suspect a fake ID. But if someone looks foreign or can't speak English, “suspecting” them can get you sued for “racism”.
"It's called the American Dream, because you have to be asleep to believe it." -Carlin