Buzzz,
Because if it is not universal it is useless.
I would not waste time trying to use it if I knew there was a very good chance that the person I wanted to communicate with could not receive my message. I have better things to do with my time that talk at walls.
The check box you suggest is not a balanced choice. Frankly, I don't think there is a balanced choice for this issue. The request should read: "Get rid of range vox."