"D.C.'s plan isn't the first to take on leave at a local level.... But D.C.'s is different in that it provides more wage coverage for an extended period, and gives workers who live or work within the District the possibility of receiving the benefit, even if their employer isn't eligible to participate, a point that's especially important in a city where a large number of people are employed by the federal government or commute to states such as Maryland or Virginia where the city can't impose payroll taxes."