Because the primary is right handed.
I enjoy asking my grandkids why mirrors reflect left to right and not top to bottom.
They do "reflect top to bottom".
Hold a written word in front of your eyes to read it.
Now flip it to the mirror to read the reflection:
Did you flip it horizontally? Then it reflected left-to-right.
Did you flip it vertically? Then it reflected top-to-bottom.
So he is not the primary?
alt Hacker News
They do "reflect top to bottom".
Hold a written word in front of your eyes to read it.
Now flip it to the mirror to read the reflection:
Did you flip it horizontally? Then it reflected left-to-right.
Did you flip it vertically? Then it reflected top-to-bottom.