So I still think that my solution is a good one - make all the parking spaces wider. And in response to (I think) Ana (yesterday), customer satisfaction = support for that supermarket = good economic sense.
Squashing in as many spaces as possible, and then certain groups having preferential treatment and getting nice wide spaces is what is causing the car park rage.
What about all the people who may have unseen problems (the majority) who don't have the right to the choice car parking spaces - e.g. people still recovering from surgery, people who walk with difficulty, overweight people, older people ...