Now that Apple leans into services revenue it might make sense to license the OS for clones, if they could still sell you an Apple Music subscription on your Samsung iOS device. But as matwood said above in the 90s they traded high-end hardware sales for much less lucrative license fees and lost badly. It was one of the very first things Jobs tried to fix when he returned, and he ended the program because he couldn't get terms he liked from the licensees. (Which in retrospect is weird because it put them entirely out of business, but shrug.)