I'm going to be contrarian and say that customary measures have evolved over time from being used for actual work. Ten is a lousy unit because you rarely divide anything into tenths. With a standard tape measure divided into 16ths, there's one half-inch mark, two quarter marks, four eighth marks and eight 16th marks. They're all different sizes, and you can just tell by looking which type a mark is, you don't have to count to know the measure. With a metric ruler or tape, you have cm and ten mm marks, the fifth one might be noted somehow but you have to count. A 16th of an inch is the smallest unit usually used it carpentry, it's half a saw blade. A mm is about a third smaller and I find it too small to be useful.
Acres and miles used to be logical but got screwed up. At one time in Europe there were two competing measures for the foot, called the short foot and the long foot. England used the short foot and most of Europe used the long foot, which was 10% longer. At that time a mile was 4800 feet and an acre was 36,000 square feet, which are great units for doing math. England eventually switched to the long foot in order to facilitate trade with the rest of Europe. Rather than redo all of the land records, all of the units of measure above a yard were redefined to be 10% longer. So a mile became 5280 feet and the acre became 43,560 square feet. This was almost a thousand years ago.
