A nautical mile is 6080 feet, but at sea a nautical mile is divided into 10 sub-units known a cables, there being 10 cables to a NM, each cable being 200 yards. It is an approximation, and the resulting mile is sometimes referred to as a tactical mile. The point here is when dealing with measurements as small as a mile, or a cable, 80 feet, or indeed, 4 feet in a cable, the difference is negligible.
If you take even a cursory look at the Nautical Rules of the Road and Aviation Rules of the Road they are very very similar. I believe the reason is that the Royal Navy was the first body charged with developing aviation in a meaningful way, and that included writing the rule books. The obvious thing to do was to adapt the rules that everyone was already familiar with.