There is also such a thing as 'prosecutorial discretion'. I'm not seeing that here, either.
Maybe there is more to this story. If there is, I'd like to know.
As for truancy laws, in my cynical opinion, they only exist to keep the 'body count' up in the schools so the funding keeps rolling in.
That is correct. The prosecutor brought up the charges. Lanny is a dang smart fellow, and there had to be a reason he gave her jail time.