To be honest I can't see what appropriate dress in a workplace has to do with appropriate dress at high school at all. I wore completely different things as a teenager to school than I do to work as an adult in an office job. Some workplaces have very strict dress codes, some don't. At a workplace you deal with people of all ages and backgrounds, and what is appropriate is partly defined by what is acceptable to all.

That's not to say that there isn't an idea of "appropriate" also in high school, I just believe it's probably a lot laxer, and closer to what teens wear at home. Personally I think she looks lovely, and very inoffensive, based on MY cultural background.