Responsibility For Being At Work On Time

My daughter walked out of here this morning, madder than a wet hen, and I feel bad for her but I am trying to teach her some responsibility. She was scheduled to be at work by 7 am....well, she worked yesterday too and then went out for an extensive lunch with her friend, got home and went back into work (she worked a split shift). This morning, she's not up at the normal time and asked me if she could just stay at home. I was not happy because she has pulled this number a several other times, leaving her job with a loss of worker. They don't like it, and I don't either. Her job is not a big conglomerate that can just call in the next guy. I made her get up and go. She wasn't happy with me and before she left, I asked her if she was mad, knowing I would get a yes. She told me that her back was hurting. I told her that she cannot just stay home when she wants to. The lifeguarding job is MUCH easier than her other job and she was okay with going to that one today. Although she has 2 part-time jobs, she rarely works more than 20 hours a week for the both of them together. I made her go this morning because I want her to learn that others are relying on her being there. I told her that after she goes, if she STILL doesn't feel good, to let her boss know and THEY can send her home, if need be. At least she has shown the responsibility of getting there on time. Seriously, I feel bad for her back hurting some, but she HAS to learn responsibility. Was I being too hard on her?