Probably because that stuff would fail if you carried it around in your pocket with your keys and folded it 8000 times, too.

If you’re talking about eInk, the refresh rate and color fidelity are unacceptable for an apple device. There are eink phones on AliExpress, though. Just don’t expect apple-level quality.

And while Moebius uses a plastic substrate, Carta and Kaleido use glass and can be pretty fragile. My Boox reader’s display cracked when I worked it out of its case.