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.
People are just realising men and women have buttons on opposite sides of shirts - Daily Star
Here's why men's and women's clothes button on different sides
Why Do Women's Shirts Button Left & Men's, Right?
The Interesting Reason Why Men's Clothes Have Buttons On The Right While Women's Clothes Have Buttons On The Left - I'm A Useless Info Junkie
The real reason women's shirt buttons are on a different side to men's - NZ Herald
Why Do Women Have Shirts Button On The Left Side?
Women button on the left, men on the right: The reason why finally explained
Why Men's and Women's Shirts Button up on Different Sides
Womens shirt buttons left Mens shirt buttons right Why ??
People stunned as they realise why women have buttons on opposite side to men - Birmingham Live
Why Shirt Buttons Are Different For Men & Women
Was this coat made in Womens style?- buttons on wrong side?? : r/filson
Why Shirts Button on Different Sides For Men and Women