Really? When I'm holding my phone (right hand), my fingers wrap around the left edge and my thumb rests along the right edge. Moving my thumb to the TouchId is easy. Moving my index finder to the center of the back panel is awkward.
For me, for 3 years, yes. For you, clearly the answer is no. Everyone is different and that is great.
OP stated:
> That touchid on back is a huge fail from UX perspective.
This is a matter of opinion that was stated as fact. I've used both styles of phone (simultaneously) where the fingerprint sensor is on the thumb/home button v. on the back for a few years now. I prefer the sensor on the back. I am not alone in this opinion. Therefore, it is not a "huge UX fail". That is the point I was trying to make.