I was with you until the metric jab. It's tiresome and ignores the complexities.
Are you going to pay the trillions it'll take to do this? And pay for the errors along the way?
The Mars Climate Observer is the cautionary tale you apparently need. And this occurred in organizations that are painfully meticulous. Now imagine changing any industry.
It's just not a simple thing, despite people wanting it to be. Go to any manufacturer that has multiple decades of ACU tools - you're saying everyone needs to retool. There aren't enough manufacturers of tools to meet this one element of changing.
I do find it frustrating that metric isn't taught alongside ACU consistently. My school did decades ago, but many of my friend's schools didn't teach it. That's a major mistake.
Things like road signs should get both Miles and KM when they're replaced, but regulation would have to be changed at the federal level first.