Now that I came across this thread I see OP's point.
To share one experience: once at MUC, I arrived with rental car the evening before my morning flight. I checked into the HIX airport hotel which is some 5km away from MUC airport. The car rental period was over and I wanted to return the car during the evening and have some excercize, so I wanted to run back the hotel. Once dropped of the car, I found that it was nearly impossible to get out from MUC without a car! No walkway, just designed to get out by vehicles. Trying to find my way out alongside the traffic and all that, I found police cars coming after me. I don't know if they thought I might be a bomb freak or something, but they followed me quite a while but did not stop me, nor asked questions. Maybe they just wanted to see a crazy man.