Also there is no law that requires that one has to be at work. So of course she wouldn't have been put in jail for not going to work. However there is a law in Texas which requires her to go to school. A law which says that she can go to jail for not attending school.
You are right that she chose what was important to her and did those things. But she also chose to not heed the warning the first time she was in front of the judge. Again, her choice. If a person decided that it was important to them to kill another person would you apply the same reasoning as you did here? I'm willing to bet that you wouldn't. What is or isn't important to her is immaterial. What is material is that she chose to skip school. She chose to ignore the warning that the judge gave her the first time around.