>But what seems to be the reason for the US hold-out to stay with an >>archaic system?
>
>Well, I think it is pretty complicated stuff to move from Imperial to metric.
The easiest way would be to repeal the laws that forbid voluntary full metrication and trade in metric only products.
For example, the FPLA is a Federal law covers packaged goods that you see in the supermarket. It mandates non-metric units on the label. A two liter bottle with a label that says "2 L" is legal in all countries except the USA. There is a proposal to change the FPLA. Many manufacturers want the freedom to offer metric-only labels (as you can see with wine and liquor) and don't want to pay the costs of relabeling just for the US.
Many Americans are unaware that non-metric units are mandatory.