As I said, SMS is secure enough without being the nightmare of a proprietary spyware app. As for fees, you have an American perspective, in most of the world SMS has been free to send for decades, and was always free to receive. The ideal solution is indeed a 2FA app, but those never took off.
Similar setup here, for same reasons. But I go further: my contact list is empty. Not a problem if your contacts are all on Signal or Telegram rather than SMS or Whatsapp. IMO contact lists are privacy scourge #1. They allow everyone to grass on their friends with zero consent.