Outwardly, I want to agree with you on this.....initial common sense says you're probably right. However, when I start thinking about how afraid of the nazis most people in this same region, if not most of Europe, were back then, it wouldn't be too hard to assume that everyone just looked the other way, and did so INCREDIBLY well, while the nazis "supposedly" hid the train. And they would do it that, VERY convincingly I might add, simply so they didn't get themselves killed!!
You gotta figure, anyone who DID see them hide it, or were even just ASSUMED to have seen them, were immediately shot dead on the spot!
Plus, based on the pictures of the area that are all over the web, the surrounding landscape looks not only dense in foliage, but is obviously a very rugged & mountainous terrain as well. Again, it wouldn't be too hard to assume that people living in the surrounding area just COULDN'T see anything going on simply because the activity was more or less hidden from them.
Then again, I could easily be wrong.
Still fun to look on with anticipation though!
All the best-
JA