It is very unfair to traders in towns and villages that car owners are charged parking fees to visit them, but not to visit out of town complexes. From an environmental point of view, it is exactly the same if a person drives from his home in the city, to the outskirts to shop, as it is for someone to drive from the outskirts into the city to shop. City centre shops also attract shoppers on foot or train far more than out of town complexes.
Traffic jams are usually much worse on ring roads and near shopping centres than in city centres. All on-street parking should be free, and councils should allow as much parking space as possible and time limits should allow at least 3 hours.
The environly friendly measure would be to charge for parking at supermarkets, but I don’t propose this, as it’s contrary to the freedom to be poor.