Why doesn't everyone have MLK day off?

Martin Luther King Jr is a federal holiday, but not every person works for the federal government, so not everyone automatically has that day off work. On federal holidays, non-essential federal government offices are closed and the employees are paid for the holiday.

While federal government employees have federal holidays off, not every business is closed on federal holidays. If you work for a private company, it is dependent on each company to choose which days, if any, it takes as closed paid holidays. Some businesses choose to be closed on federal holidays, but many do not, and many also take off some days but not all eleven.