I'm being a bit pedantic about the "every fingerprint reader" mention and am assuming that mention also includes non-Apple devices. HTC and Samsung phones have, in the past, stored fingerprint images in an accessible location. What's worse was that the fingerprint image would be refreshed with every swipe/finger touch!

[1]: https://www.theguardian.com/technology/2015/aug/10/htc-finge...

[2]: http://betanews.com/2015/08/11/htc-and-samsung-phones-storin...