It was said by an American writer, I believe, that traditions are solutions to forgotten problems; and abolishing the traditions brings the problems back again....
For example, the 'decimal' currency was neither wanted nor needed: £sd was its superior as an internal, market-place means of exchange, but - to the fury of politicians who wanted to convert Britain into a mere northern province of Europe and metric-minded bureaucrats alike - the duodecimal shilling stood like a bastion against the decimal marketing, measuring and resulting control so urgently desired by the Napoleons in our midst. The three-stage money system was also very easy for mental calculation* - one almost never needed to count above twelve or twenty when shopping, and fractions were readily found - and thus was highly resistant to inflation. A price rise from 34p to 36p passes unnoticed today; but a rise from 6s 9d to 7s 3d would have caused an instant drop in sales. Inflation was desired by certain very powerful pressure groups at the time and so, for all these reasons, £sd had to go.
The government immediately launched a two-pronged attack: 'going decimal' was promulgated as 'moving with the times' (despite actually going back to eighteenth-century ideas); and a very clever diversionary tactic was set up by the deliberate initiation of arguments (using TV and the press) as to whether a pound or a ten-shilling unit should be adopted, so providing a large, juicy red herring to lead the public away from considering the loss of a thousand years of cultural history and development (yes, I did say development: £sd had continued to evolve after the Americans and French had frozen their money into decimal rigidity).
Measurement was built-in: the halfpenny was made precisely one inch in diameter so that a humble coin could double as a quick check on size. The dodecagonal threepenny-piece which was introduced in the1930s, replacing a small silver coin, emphasized the duodecimal base.
Americans had at least the sense to hang on to rational measurements, but should be warned by what happens in Britain if they want to keep this freedom.
The US system of government is more open than is ours, but the metricators will probaoly try the same tactics as they do here. Cut-off dates, for example. We all thought that tea, our national beverage, had escaped: tea was happily being marketed in 4oz and 8oz packets (with the 'bag' variety in multiples of twelve) long after the Metrication Board had been disbanded by the redoubtable Sally Oppenheim when - suddenly - it appeared in packs of 125g and 250g and the ounces vanished. Parliament had sat at the end of a session, with few (selected) memoers present, and had passed legislation 'on the nod' (no debate or formal vote) which set future cut-off dites for oz/lb selling of a whole range of foodstuffs and commodities. This was not reported at the time on TV, etc. MPs were themselves ignorant: I conducted a heated correspondence witn a margarine manufacturer on the strength of my MP's assuance - in a personal letter - that there was no cut-off date for margarine. There was, however: the manufacturer had been informed, out my MP had not. (Another cut-off has operated very recently, ending dual capacity marking on ketchup bottles, etc.)
So, beware, US citizens! Cut off dates are the metricators' time-bombs. Are there any planted under you?
* And this was a time when most people could do arithmetic!
Thoughtful research, however, must continue. If a new idea is to be a genuine improvement over an older one, it must retain the virtues of the older and add virtues of its own. It is precisely this principle that the French lost sight of in the 1790s, with their cart-before-the-horse notion of trying to constrain unconstrainable natural proportions to an inefficient and unnecessary arithmetical straitjacket. It is for this reason that we must preserve our customary, rational system of measures against the onslaughts of decimalists (who fear it) at least until it is superseded by a wholly better arrangement.
From the mathematical point of view it is somewhat inconvenient that Cro-Magnon man and his descendants did not have either four or six fingers on a hand."
Boyer, Wiley: A History of Mathematics USA 1968.