An extreme example of the consequences of #7 is the Lake Peigneur disaster, where "an engineer mistook transverse Mercator projection coordinates for UTM coordinates" and Texaco, drilling for oil, drilled into a salt mine that was under the lake. The lake drained into the mine (which had 55 workers, all survived), the canal that normally drains the lake into the ocean reversed until the mine filled up and reversed again, and the lake changed from freshwater to saltwater.
https://en.wikipedia.org/wiki/Lake_Peigneur