Huh? Compared to a stylus, your fingers are really fat, and mobile operating systems designed to be controlled with your fingers make it so that there's a bit of give on what gets accepted as a press, because half the time, where you think you're pressing with your finger won't match up with the precise location you're actually pressing, and you'd get very stuttery scrolling. That doesn't mean the screens themselves can't recognise precise touches, it's the software behind the screens that's optimised for an entirely different use case.