I understand your point, but the concept of personal contact with a student on their personal phone is a very fine line that could be viewed very negatively by a very small, but vocal subset of parents.

Also, the software that you're referring to, in my experience, is targeted for the parent, rather than the student. Its twofold better in that there's less ethical liability in parent communication as opposed to student communication, and these tools include the parent in the education process. They know about grades, attendance, and other things and can then take a more targeted role in their child's education.