[TeMPOraL]

It's not a technological choice, at least not at the level of camera design. It's trivial to record videos the right way; people just can't be arsed.

Suppose you implement horizontal recording while the phone is vertical; this would mean the video preview is now scaled and takes only a fraction of the screen (the same way watching horizontal video on YouTube while in "portrait mode"), which people would find annoying.

Alternatively, you could not scale the video; now the video preview displays only a vertical slice of the frame. It looks OK, but people would soon discover the actual video a screen's worth of image on each side of the preview, leading to anxiety and worry - people would have pay extra attention to not capture things that weren't intended to be on the video; they'd soon look for a way to turn this off.

The unfortunate reality is, it's a social problem partially caused by a technological one. Vertical videos are driven by the phone form-factor and because portraits and selfies actually need to be vertical, and people being people, shooting photos of themselves and other is what they care about the most.

[ddalex]

So this comment and the sibling mentioning square sensors raise some good points. Let me rephrase the technological challenge: Make all phone screens square. All phones are now squares. Use Generative AI to fill in the sides of non-square screens. Problem solved. I think I need to make this an AI photo startup.