Why is Lincoln facing backwards on the penny?

Answer 1

He's not. There's no backwards or forwards, OR right or wrong, on coins. The designer (Victor D. Brenner) copied the image from a medal he had made earlier, and simply chose to have Lincoln facing to the right.

It was purely artistic coincidence that later coins had the portraits facing to the left. In recent years the direction has changed again. The portrait on the 2005 Jefferson nickel faces right, like Lincoln, and later nickels and all Presidential dollars face forward.

Answer 2

There is no "forwards" or "backwards".

The coin's designer, Victor D. Brenner, based the portrait on an earlier image that had him facing to the right. in 1909 no other presidents had been pictured on coins so the decision was entirely arbitrary. The choice of leftward-facing portraits for later coins again was solely an artistic decision.

Note that Jefferson's image on the 2005 nickel also faces right, and his image on later nickels faces forward as do the pictures on the Presidential dollars.