iPhones are too thin for a fingerprint sensor on the side. Placing one on the back would make sense. A lot of android phones have fingerprint sensors on the back, which I find much easier to use than the front sensor. I just brought a phone (Ulefone Power 2) with a front fingerprint sensor. It sucks having to use both hands to reliably use the sensor. On the plus side, it's got a 6050mhA batteryJust put the fingerprint sensor on the side button. Then you can have a all screen 16:9 display. Is it really that difficult?