The excuse is the same one used by general contractors everywhere — “I don’t control the subcontractors.”
If they had any ethics, they would check up on the sub contractors after awarding the contract. Why after ? Because calling in labor department officials and IRS after work has begun, letting them fine and punish the subs, and then using the contract to force the subs to complete the work using legal workers would force the sub to take the LOSS.
If you just reject the bid from the start because it seems unusually low, you are just passing the buck and the sub will find another customer.
If every American worker who became aware of illegals or labor law violations anonymously snitched on the employers, we could end illegal immigration.
Give everyone who calls in an illegal jobsite $500 per worker caught. Then fine the employer $10,000 per worker and it cannot be washed away in bankruptcy. BTW, no gov’t bennies to illegals. The US will empty out faster than....