reversal of computer camera image
Cameras in general are mirrored - all the way back to analog film.
The sensor being placed behind the lens means that the lens creates a mirror image of the world (in front of the lens) on the sensor, and the sensor merely senses the light as it lands on it.
It's more of a convention - in the analog film world, the negative (sensor) was mirrored as well. The positive was created by projecting the negative (shining light through it) onto a final (enlarged) screen print.
This is still actually the case in the projected display setting - so essentially the LCD or DLP inside a projector needs to be mirrored, in order for the image on the screen (again, behind, this time, a projection lens) be correct again.
Now, it's desirable because:

the inversion is simple in software, and actually doesn't matter at the intermediate stage, you just need to correct it before final display
the historic setup when the viewer was behind the camera, makes it more natural

It is challenging with the 'selfie' cameras, where you are essentially staring into the camera, and attempting to view the image from the camera on a screen directly below. Then people prefer to be able to move in the same direction as the image on the screen.