App Store requires password even though I set preference for touchID

Whenever one of the children on my Apple Family account requests an app on the App Store I have to enter my Apple account password instead of using touchID. I have set the preference for TouchID to work for the App Store. (I've also set up my Apple account to use a passkey, but that doesn't seem to work across the entire Apple ecosystem.) At a minimum, though, I thought the preference to use touchID for the App Store should allow me to approve apps without having to enter my password. Why isn't this working?