Wow, that's the first time I've seen 500+ comments on an HN thread about cycling!
As to the "Dutch" grip: when I did driving school in Germany some years back, my teacher took great pains to impress on me to always look back before opening a door. In fact, not doing so can cause you to fail your driving test. As having to retake your driving test here can easily set you back several hundred euros, I learnt quickly...