In my experience in food manufacturing, the big companies get a better price on raw materials because they can buy in greater quantity... that gives them in edge in final price over the smaller guys... one of the ways smaller companies have found to maintain competitive pricing is by employing illegal immigrants... they don't ask for raises, don't complain when they're shorted on pay, etc... and if they supply the company with an ssn that matches the identity they've supplied, the company isn't really liable...
i worked for one company that would just give new employees the ssn and name of a past employee... made it easy for me... the sausage maker was always named jorge, no matter what he looked like...