I did not destroy anything and even if I did that is not automatically vandalism. Please actually read the linked wiki article. Do you really think that someone with way more mapping experience in his account is going to randomly vandalize?

The layer tag does not imply that the POI are anywhere. It has absolutely nothing to do with that. The POI may have level tags to tell on which floor they are at. How do you come to your conclusion? The layer tag only implies that the building is "over" the service highway. This is needed since the two features intersect. The layer tag does not indicate if anything "touches" the ground or not. Again, please read the wiki about layers.