A great many people mistakenly believe that ALL employees are entitled by law to Federal holidays.
This is not the case. Federal holidays are guaranteed to Federal employees only. As Beth pointed out, private employers are not required to offer ANY holidays, Federal or otherwise.
Consider. Hotels do not close on holidays - in fact, holidays are their biggest work days. Someone has to man the desk and clean the rooms. Hospitals don't close for holidays - someone has to care for the patients. Many restaurants don't close - someone has to cook and wait table. Police and fire stations must be staffed. And you can bet that there'll be a lot of people doing their shopping on December 24 - retail stores won't be closing. Someone has to be there.