Constitutional Right

I find it quite confronting when opening a door to a shop or at the entrance to a railway station, to see this sign  prominently displayed literally at eye level and in my face, then to read these type of headlines

Toddler shoots, kills mother at Walmart store in northern Idaho

A two-year-old boy shot dead his mother when he pulled a handgun from her handbag and accidentally fired it in a Walmart store in the US, police say.

Why, I wonder, does a person going shopping need to have a gun in their handbag, particularly when there are small children in the vicinity? It is beyond me why this "right to bear arms" is such a part of everyday life and so hotly defended when this type of "accident" is all to frequent.