Good point, I've heard that supermarkets don't even try to clear the car park as it can make them accountable should someone hurt themselves on the icy bits that will inevitably remain. That could be b*llocks like but it does make sense in a weird way.
I heard you're not supposed to clear the paths and road outside your house for this reason. Oh well. ...saves me a job
I don't know how true it is, but I am under the impression that if you clear the snow from your property and someone slips on the ice then you are liable, but if you do not clear it and they slip then they are liable. I heard this years ago when someone on our street had a mini-snowplough and cleared all the paths. Unfortunately it became a big layer of black ice on a hill and anyone stepping on it was likely to end up on their ass two doors down!