It really doesn't seem political as you present it, along party lines. No one wants to incur the cost of switching, which would be increased errors and material waste. The politicans who change it will be associated with the one time increase in errors and confusion. The benefits are reaped slowly over time (in the form of fewer conversions), so no one can really claim all the credit at once.

It's also not political insofar as whether we use metric or imperial de facto depends on the decisions of many thousands of manufacturers and suppliers, not the government. Are they going to outlaw all the imperial measuring tapes, or institute a buy back program?