A text message is far less immediately intrusive than a phone call. The recipient can finish what they're doing, or at least reach a convenient break point, before they even reply to you. And you can even say "Call me when you get a chance", thereby removing any necessity for you to initiate a phone call at all.
Even though I know this intellectually, it's still hard. In part this is because even though I have a phone with a (tiny) keyboard, it's still a complex operation and I'm always screwing up, hitting send or back when I meant backspace or delete.
But part of it is something weird that I still haven't figured out.
But part of it is something weird that I still haven't figured out.