The Rated...the last one is easy.
If there are no doors and no locks then legally the store can be declared a public thoroughfare.
Some cities/countries will have gates or chains at shopping center carparks and require them to be closed for one day a year to re-affirm clear title over the land.
My Aunt once had a gate in her back fence so people from behind her could pass through her place to the tram out front. Many years later she tried to deny access, as the neighbours had changed and she was not able to. After a given time it was deemed public access...