Well, yeah, but USA uses imperial for a different reason.
USA is a huge place, using metric system would be confusing while imperial is made for imperial scale, which in case of USA is kinda big so it fits like a glove.
If I were to give a solid reason, it's hard to change constants.
Do not forget that engineers in the us use imperial. It's only the scientists that have adopted the metric system. And all engineering equipment is designed to be used in imperial. All schematics, engineering projects, the whole lot.
It's a logistical and infrastructural nightmare to redesign all your package, building, machinery standards. Because if you don't do that, your 3 oz can will become a 88.7205887 ml one. The 10 foot story to a 3meter and 48milimeters... etc.
Also, go to an 80 year old and give him a car that has a speedo in km/h, look at how he will react to it.
There are many failed attempts from the metric side as well. The 10-hour day is probably the best known.
