When United leaves someone a voicemail, asking for a call back, shouldn't United also say, "if you call us back, it'll cost $25"?

I do recall when I was on hold, waiting for an agent, there was an announcement about "fees may apply" but the agent never mentioned it, and it definitely wasn't clear to me that I'd be charged $25. Based on the voicemail I got, all UA needed was just an updated credit card number; based on that I didn't view the call back as making a reservation.

(I'm well aware that if you call UA, it'll cost you to make a reservation.)

Very irritating, and this is an example of why people dislike airlines.