In re: Why signatures are still used & insisted upon in the banking sector?

I haven't understood as to why signatures are still used & insisted upon in the banking sector. Signing is inconvenient, particularly for older people.

In this era of biometrics It's time to return to thumb impressions - both digitally & where needed, physically.

PS: I find it extremely difficult to sign, write cheques or do anything with a pen/pencil.