Most of the time when I open an application and want to search something, the search box will be put at the top of the screen. With today's screen sizes I find that often I have to move my hand, or reach out with my fingers to the extremities at the top. Then, after I've finished tapping at the search bar, I have to move my hand back to the bottom of the screen to continue typing.
Yet many guides I see (such as this one from UXPlanet) suggest putting the search box at the top of the screen.
That gives me the question: why put the search box at the top, given that on mobile it's easier to reach the search bar and continue typing when it's put on the bottom?
Google's new Android Pie puts the search bar at the bottom (image taken from Android Authority's Pie review):