President Obama’s health-care law will force businesses to buy insurance for their employees or get slapped with a fine. But one category of employers will be spared that expense: businesses with fewer than 50 workers. Many of the roughly 4.5 million businesses that employ fewer than 50 workers are familiar restaurant franchises: Burger King (BKW), McDonalds (MCD), Subway. These companies use lots of part-time workers and are unlikely to pay them full health benefits, given the high cost of providing insurance. Many of these part-time workers are poor enough that...