Big Deal

I'm always expecting security to warn me off taking pictures in supermarkets, as over the years quite a few photographers I know have got into 'trouble' doing this.
A few years ago one of them was taking portraits in the car park of customers holding up their shopping, within a couple of minutes security had told him to stop what he was doing immediately!
I don't know what they are so paranoid about, one of the explanations from them is to stop industrial espionage! As if...
Why shouldn't we be able to document the way we live and these days supermarket shopping is a big part of life.