The two biggest benefits of online education for the K-12 years are the access to a broad range of high-quality teachers along with much more flexibility in the student's program coursework. An online program allows a student to learn at a pace more specific to each child's needs.
Even though bullying has made itself apparent in social media, it is arguably less of an issue with online schooling than in a traditional classroom setting. Students in an online program can stay on a home-based diet, as opposed to eating foods that may go against household moral codes and ethics. A students exposure is also limited in this manner. Which for many parents is a great benefit, considering all the different things that are brought into public schools today.
Another big benefit that has made itself apparent is that students respond actively well to online educations. They relate better, and show a greater response to the lessons that are being taught to them. Case studies have been written that explore the how, and why surrounding this. One of them is that the lack of distraction from all of the social pressure of schooling allows the student to focus more. So, the exact reason isn't known as to why this works. But it does. In the long run, it's less expensive for taxpayers, more efficient for teachers, and the ones that need it the most, the students, are getting the most out of it.