Stands to reason that if Samsung can't make the sensor work with their OLED screens, and rumour is that Apple is buying OLED screens from Samsung for it's iPhone 8, that the sensor wouldn't work for Apple either.
On the other hand, Samsun doesn't create the touch layer on top of their screen, so that doesn't necessarily follow that Apple can't do it. In fact, the touch sensor on their laptops is giving them lots of practice. And their front-side touch sensor on their phones is glass, and there are no problems with that kind of thing happening.
Secondly, there is no way Apple will place a fingerprint sensor on the ergonomically dead-end on back. Zero chance.
Samsung's biggest problem was Microsoft's back in the past two decades. Vapor is the word. Look it up. They over promise and under-deliver on a regular basis. Apple rarely does the same. And that's why they sometimes appear to be behind. They're not. They're just waiting for the right time, considering user experience more important that being like the proverbial forum poster who gets on and types "First!" in the comment section. We don't respect them, why should we respect the technological equivalent?
This is not a problem for me, having used both front sensors in the home button and rear sensors on he back, I don't want a front sensor. It causes a number of headaches mixing the fingerprint sensor with the home key, payment approvals through Finger ID going to home instead, Going home when you attempt to reopen a session where the screen has locked.... Give me the practical sensor on the back, particularly when you can use it for other functions through swiping as well.