I don't know why you say that the toes (in the image from the site of Von Daniken) seem to be "painted". It doesn't seem to me so evident, but I'm not an expert.
In the past, it has been common practice to paint features in the rock to make them more visible. I have seen this in some of the dinosaur beds in the Morrison Formation. From what I can see, take away the black paint and the humanness of the print is gone.
A couple of items:
1. Would be easy to eradicate evidence of tool marks. After all, these were abraded sand grains comprising the sedimentary rocks and a season of running water would soften artificial tool marks to the point of disappearance.
2. This track does not look human to me at all. I walked on a beach a couple of weeks ago and I saw thousands of tracks, but zero that looked like this. The depression in the sediments is simply that: an elongate depression (with toes painted on).