Do you have short term disability? Many people use that. Depending on size, your agency may also have a leave bank that may or may not cover maternity. My guess is that they don't want to deal with the hassle of reporting pay to DPFML every quarter and withholding-- and some people probably don't want them to because it's money out of their paycheck for a program they'll "never use". It's unfortunate, paid leave should be available for everyone.