Why can't my job work that way?

Overheard in the elevator at my office

Girl 1: What time do you have to be back?
Girl 2: Well...I told them I was taking my mom to get her car. *Laughs*
Girl 1 and 3: Laughing
Girl2: If I'm late I'm late. I don't care.
Girl 1: Yeah...
Girl 2: That's what I love about being Salary instead of Hourly. I can work whatever and get paid the same amount every time.
All 3 girls: Laughing

Can anyone else guess how long she'll keep her job?