IIRC, it's because the ARM designs tend to use camera modules that come from smartphone-land.

Cameras used on x86-64 usually just work using that usb webcam standard driver (what is that called again? uvcvideo?). But these smartphone-land cameras don't adhere to that standard, they probably don't connect using USB. They are designed to be used with the SoC vendor's downstream fork of Android or whatever, using proprietary blobs.

A similar thing is happening in Intel land recently, where the cameras use ipu6 / ipu7 chips rather than dumping simple frames over USB. But this way we get a higher resolution / quality at least.

It’s usually MIPI or some variant. There’s probably a way to enable the video stream but you also have to talk to the control module itself which is on a different bus.