Most people touch the side of their hand to the page as they write with a pen or pencil. Latin is written from left to right, and culturally its heritage somewhat demonizes left-handers ("sinister"). Left-handers also have difficulty writing LTR with wet ink, because their hand smears the ink as it crosses the page. (I bet this once made for a lot of enthusiastic left-handed European students of Arabic and Hebrew.)
Two apparent remedies are writing without touching the page at all, and learning to write with the nondominant hand. At least for me, both of these are quite challenging. (Two more modern adaptions are the ballpoint pen, whose ink dries rapidly, and pencils, whose deposit is not wet.)
What tools or techniques existed in the brush, reed, quill or fountain pen eras to allow left-handers to write LTR text, or vice-versa? Similarly, how did Greeks with reed pens manage to scribe a boustrophedonic text, which alternates between directions?