Most of the danger is on the pulling out side, so it makes more sense to do the harder ones for the safer part. Plus, when you’re parking, it’s easier for others to predict what you’re doing, whereas pulling out gives more opportunity for someone walking by the line of cars to be surprised. If you’re pulling out forwards, it’s trivial to see someone about to walk in your path. If you’re backing out, you might not even be able to see someone who is 1s away from stepping in your path, especially if they are coming from your blind side.
Most of the danger is on the pulling out side, so it makes more sense to do the harder ones for the safer part. Plus, when you’re parking, it’s easier for others to predict what you’re doing, whereas pulling out gives more opportunity for someone walking by the line of cars to be surprised. If you’re pulling out forwards, it’s trivial to see someone about to walk in your path. If you’re backing out, you might not even be able to see someone who is 1s away from stepping in your path, especially if they are coming from your blind side.