Because the Boston Globe was looking into it. From the paper, posted a short time ago:
Mitt Romney, who has taken a tough stance against illegal immigrants in his quest for the Republican presidential nomination, has continued to employ a company that uses illegal immigrants to do lawn work at his home.
Responding to inquiries from the Globe, which had observed the work taking place at his house and interviewed the workers, Romney tonight fired the company for failing to comply with the law…
Romney has made illegal immigration a central campaign issue in his bid for the nomination. At last week’s Republican debate in St. Petersburg, Fla., Romney was quick to attack Rudy Giuliani for safeguarding illegal immigrants in New York City.
Yet early the morning after the debate, immigrants from Central America who say they are here illegally were in plain view on the lawn in front of Romney’s salmon-colored mansion in Belmont. Chatting in Spanish, they hustled to rake massive clumps of leaves, dump them in barrels, and clear debris from his tennis court.
Their boss, Ricardo Saenz of Chelsea, was the same man who for a decade brought illegal immigrants and others to work for Romney, whom he had met through their shared Mormon faith. A year ago, the Globe broke the news that illegal immigrants landscaped Romney’s 2.5-acre property.
In the past two months, the Globe observed Saenz and his crew at Romney’s estate once a week, except during the week of Thanksgiving…Last Thursday, the Globe interviewed two of the three workers who were at Romney’s house. Both said they were illegal immigrants from Guatemala; one of the immigrants said the third worker was also here illegally….