If we disregard a small command line utility and look at a larger software package, so that it already does network connections (or won't function) then the key

If we disregard a small command line utility and look at a larger software package, so that it already does network connections (or won't function) then the key thing is TRUST. That can be achieved by organizational transparency, open protocols, open source. It's hard and slow to build and easy to tear down. But if you use the software, you trust the provider. The simplest argument for this is: if you don't trust the provider then why on earth would you trust that the "no" actually means no!? The compromised or evil organization would send your data anyway. And if they are really evil they wouldn't do it as part of the telemetry they'd just exfiltrate it in whatever way necessary. That's why I think the telemetry thing is a much smaller issue than it seems when it comes to privacy. It's already blind faith.