Because it's too expensive. We don't have the mobile phone infrastructure in place to support it. Very few customers have phones that support it. In many countries, they haven't even allocated any frequencies for it yet.
Cost is one issue, but 'value' and other issues such as national and personal data security are becoming evermore important as the backlash against big tech, cyber vulnerabilities, misuse of personal data and messaging, and mistrust of overseas technology companies grows.
