https://wccftech.com/iphone-x-no-touch-id-ever/

Touch ID was an iconic security feature embedded beneath the home button that started out with the iPhone 5s release. Fast forwarding to 2017 and with the imminent release of the iPhone X, no home button obviously meant that Face ID was going to be the next best thing in replacing Touch ID. However, there were rumors and even prototypes that revealed Apple’s intention to mount Touch ID at the back or under the display but the Cupertino tech firm has refuted all of these claims.

Dan Riccio is the Senior Vice President of hardware engineering stationed at Apple and according to an interview with TechCrunch, the toughest challenge that presented itself with the release of the iPhone X was finding a suitable replacement for Touch ID.