I guess the point is: we have to have a good way of making businesses hang their butts out if they don't check, and we have to have a way for them to cover their butts if they check.
A web page isn't enough. It is too easy to change the address that you check in the human resources department, and "someone" in the human resources department would be amply paid to make the switch.
Fraud is rampant anyway. Too much money to be made by hiring illegal aliens.