I am guessing here: once we are proficient at reading we start recognising word shapes, not letters. In the mirrored writing the word shape as a whole does not

I am guessing here: once we are proficient at reading we start recognising word shapes, not letters. In the mirrored writing the word shape as a whole does not change - it's just mirrored, which makes it easier to recognise than if the letters are reversed. Here's the text from your link. Which is easier to read, this or the PNG? 'This example of boustrophedon text eht rof yllacificeps nettirw saw Wikipedia article on this ox turning txet htiw llaw a gnirevoc fo dohtem in ancient Greece and elsewhere.'