Do the math. One million illegals per year times the $90 quoted in the article (an amount which strikes me as very low) totals $90 million per year.
Maybe not a huge industry, but not peanuts either.
That's a lot of money, for sure, but you gotta figure in the cost of the paper to print fake ID's on, and expenditures for lamination, too. This stuff adds up, slowly chipping away at the bottom line...