I work with CaptionAccess, which provides the type of services covered in the article. One reason there isn't more captioning is because people associate captioning with disabled people and accessibility.
The article began with people looking into captioning as a means of meeting an accessibility need (a speaker losing a hearing aid) and ended with the discovery that there are many other benefits beyond accessibility. It was a great read and everyone won. Many planners never get to that point.
The lack of widespread real-time captioning isn't a technical or cost issue, it's an education issue.