Why do people claiming to have the right to shop in a  store without a mask even if the store requires one?

Do three year olds have a right to throw kicking and screaming tantrum in a store? No but they do it anyway just like those self centered and childish people who refuse to wear a mask.

Stores are on private property, sure, but they can’t set their own rules.  They still have to abide by all applicable local, state, and federal laws.  Throwing all laws out the window just because they’re “on private property” would be highly illegal and make them subject to getting into lots and lots of trouble.  Which is why businesses cannot legally force someone with a disability to wear a mask.  

Because people are stupid.

ADA laws give them that right.   Many people have health conditions that could be worsened by wearing a mask

You CANNOT ask someone if they have a health issue tho.   If someone is not wearing a mask, you are suppossed to ASSUME they have a health issue that prohibits them from wearing one.

Theres no medical reason why someone cant wear a shirt- or some kind of cover-up.

Any medical reason for not wearing shoes..  The person would have custom orthotics or a medical boot of some kind instead to further protect the feet..   Theres no medical reason to go barefoot.

Your correct .Stores are private property and they have the right to set their own rules especially when there's a health risk to their customers  and employees.