Well, they are simply the upgraded version of flat heads. They’re better in terms of ease of use. With flat heads screws, the driver tip tends to slip off of the screws when using too much torque, which could cause an injury to the hands. Even I suffered one when trying to fix kitchen door hinges.
But with phillips head screws, the driver tip stays in it’s place in the center and won’t slip off. This enables us to use motorized drivers for them and same would’ve been difficult with normal flat head screws as the driver would slip off.