Lightning is smaller than USB-C. That alone makes it more desirable for space-obsessed Apple. I think it is more robust and easier to clean too.

The thinnest smartphone ever sold was the Vivo X5 Max, which was 4.75 mm thick, and it still managed to squeeze a headphone jack into it, despite Apple's protests that such things are impossible. USB-C (2.5 mm) is significantly thinner than a standard headphone jack (3.5 mm). Between the screen, the circuit board, the battery, and the back cover (including the camera lenses), you're never, ever going to see a smartphone too thin to fit a 2.5 mm port. This is a non-excuse.

And lightning is usb2.0 and what it can do to be backwards compatible and offer 240w or more for charging and gigabits of data transfer like latest usb-c is unknown. But what we do know? Usb c is superior and it has been for years and Apple didn't switch to it on phones to sell users proprietary accestories that connect only by that port