That's very different--that's on my own hardware, and my fingerprints don't leave the phone. This is amazon's hardware, and they store the fingerprints in a centralized database.

Difference is that a fingerprint is only stored on your device, and it's just a single print.

This is your entire hand, and it's stored off-site and owned by a company who at any point in time can change their mind about that data and sell it to whoever will pay for it.

This is completely incorrect.

I use biometrics locally with my phone, but do not transmit that data to Apple, to Amazon, to MasterCard, to anyone. All they get is the usual credit card info.

Amazon it trying to cut out the middleman here, but the middleman they're trying to remove is under my control, and Amazon definitely isn't, so the shift is enormous.