Go ahead. . .get those illegals to join your union. No employer is going to risk employing illegals if they have to pay them the same as they pay American citizens.
They don't risk it. They are only required by law to ask a potential hire to provide "proof" of being "legal." Any illegal can pick up a phoney SS card, drivers license, even a birth certificate - so well duplicated as to fool law enforcement - for about $400. That's all an employer needs to see. They don't run checks to verify, and they never check citizenship status - and the law does not require that they do. Even police officers are forbidden in most jurisdictions from doing so during stops for traffic violations (Recall the recent stir when an Arizona sheriff proposed doing that?). So, how many well-paid illegal alien construction workers are out there? Who knows? The unions don't care and they are signing 'em up!