I'm left handed, but from what I've been reading of the comments on this thread, I think I might be using my phones like a right-handed person. I do pull the phone out of pocket or purse with my left hand but quickly switch it to my right hand and unlock with the right thumb, usually, on my iPhone 7Plus or HTC 10. All other phones I use a passcode because my prints rarely work. I navigate the phone with my left middle or index fingers usually. On an SE I operate one handed using the right thumb. So...am I a lefty or righty phone user? ??😕??
Anyway on the S8 it feels natural for me to use my right index finger to unlock.
It IS a stupid place for a fingerprint sensor but it sounds like Apple is also having a hard time packing similar feature set into the iPhone of similar bezel-free design. If they were working with the release date the S8 is seeing, I wonder what they would have done.