You don't phone someone for a simple message, you do it because you know a back-and-forth conversation is needed. Which is always significantly faster than text.
I think what's really going on is that people who grew up analog don't see textual decisionmaking as "real", and need a familiar voice call to make things feel "official".
For me, my team is mostly +15 or +8 hours from me. So relying on voice is just impractical.