I live in Kentucky. The schools in Kentucky are very very good. They go out of their way to give you the best education you can get. It's actually rare to have a bad teacher. They have tons of extra curricular classes. The list goes on and on of after school stuff there is to do also, including for weekends. They go out of their way to interact with the students parents also. It really is a lot of hands on stuff. They take every single issue of racism, fighting, drugs, very seriously. If you do get in trouble, detention they usually have you work on school work, and make sure you have your homework and things to study from each teacher so you don't fall behind. After school detention is usually held on Saturdays as to not make you tired after school during the week days. If you get suspended the teachers make sure you have all your work to do that will be for those days. They even sometimes will call you or your parents to make sure that you have everything up to date, as to not fall behind. They usually provide therapy for students and parents, for the day and after school. Sometimes including weekends. They also have parent classes to teach parents how they can more help their children. In 3 out of 5 schools I went to they also had daycare for any students who had children early or even any students parents, for free.
Not only this, but in Kentucky it is very easy to get welfare, SNAP (food stamps), and assistant living. Oh, and health care. You can literally get most of this within a day of applying, unlike most states you would have to wait weeks, up to months. Assistant living maybe takes a week or two, but that's still extremely fast. Making education as you would guess a lot better also, because worrying about money isn't something a lot of people actually have to do. Also the cops in Kentucky are usually extremely nice, and willing to listen. They are even more likely to give you community service and help you out in court if you get into trouble, then to immediately just throw you in jail.
Could the schools be better? Yes. Is there some instances of issues in Kentucky schools? Do they need to work on taking religion out of the schools, yes. But most of that you, yourself have to go to and sign up for, like Christian clubs. So, yes could be some improvement.. but overall the experience is amazing.
The reason I'm saying this is because
I honestly doubt that this is actually a school rule, and she got in trouble from it. All of the schools I went to, there were girls including myself, who wore a lot less. If it is, she was undoubtedly asked to change in school and offered clothes. (Because they do this. Was asked to change clothes multiple times, and take out piercings. My own fault though.) If they did send you home right away, it's most likely because you told them no that you weren't going to change after trying to talk to you multiple times.
If it is, it's probably for a good reason. Or something you can bring up during parent meetings. They do actually listen to the parents suggestions, and students.
The school systems in Kentucky are amazing. I think it's stupid if she did get sent home, however I also think it's stupid that you're complaining about a rule, when you are going to probably a very very good school, compared to the rest of the US. You were most likely offered clothes, spoke to multiple times, and you just said no. So at that point it's your own choice to be sent home, instead of waiting for after school or during a school meeting where your parents can bring up the overly strict dress code. Instead you probably said no, let your pride get in the way, miss that day of schools classes, post a picture and put it up on Reddit, you and your parents will complain, and most likely not show up to a meeting where something can be done about it to change the overly strict dress codes.
Source; went to 5 different schools, in different parts of Kentucky. Coming from Ohio, I can say that Kentucky was fucking amazing, and gave me an experience that I was very lucky to have. So great in fact, it's really annoying to see anyone complain about something so fucking stupid.