There are a few theories as to why men's and women's shirts button on different sides. They range from gun access to breastfeeding needs.
Men's and women's button-up shirts are on opposite sides for this reason
Why the buttons on men's and women's shirts are sewn on opposite sides - Mirror Online
Why men's and women's shirt buttons on different sides
Why are men's and women's clothes buttons on opposite sides? – uniontailors
People are just realising men and women have buttons on opposite sides of shirts - Daily Star
Unusual reason buttons on men's shirts are always on the right and women's are on the left
Why are men's and women's clothes buttons on opposite sides? – uniontailors
Was this coat made in Womens style?- buttons on wrong side?? : r/filson
The Shirt Ontology
Ever Wondered Why Men's And Women's Shirt Buttons Are On The Opposite Sides? Here's Why!
Here's Why Men's and Women's Clothes Button on Opposite Sides, Smart News
Why men and women's shirts button up on different sides