She was not a solicitor, that is quite right, but as with all multi million pound retailers they are always updated with the latest legal responsibilities, yes they have to grit all ares of there store, but where informed that as soon as you do, you are admitting liability if you miss a patch and someone slips.
I could not possibly grit all areas where i leave water so i either leave it as it is, or work another day, or later in the day.