It will be a bit stupid not actually back up the keys to once funds, not only could your lose it when you die or something happens but you also will lose it when something happens to the device. So I doubt any one will actually have a wallet with backup, Infact that’s the first thing that comes when creating a wallet, except if you’re referring to an exchange account which is not what OP is referring to on this thread.
More so I think almost all biometric authentications are backed up by passcodes. So that should any of your state fears against them (biometrics) arises you can simply just use the passcode
We can stop talking about wallet backups but just know that there are people who don't make wallet backups. If you do it, it's good.
I am against biometrics but I know it has advantages and disadvantages but with me, after consideration, my opinion is the same, against it.
High risk: You can change passwords, but you can’t change your biometric details. If your biometric data is stolen or lost, it could be permanently compromised.
Duplication: In some ways, biometric credentials are easier to obtain and duplicate than access cards or keys, because we quite literally leave our biometric footprints and fingerprints everywhere we go. Criminals are learning to copy biometric details by lifting fingerprints off glass, or even capturing voice recordings.
When your biometric are stolen, data base is compromised, you are done. Because simply said, you can change your passwords billion of times if you want but you can not change your biometric.
It sounds seriously but I am against Fingerprint Biometrics for kids. We as parents should not leak our kids biometrics easily like this.