I guess as one of the biggest economies in the world, the US has not felt a pressing need to convert for the convenience of others.
If you look at Australia and UK, I think you'll find that most older people, and I don't mean decrepit old either, are perfectly familiar with terms such as feet and inches, who feel quite at home if told a baby weighs in at 7lb, who have a clear mental image of what a day of 90F feels like etc
So we're walking around, able to work reasonably comfortably in both systems.
But that's because we were forced to.
I read the article and how the people using the petrol station felt cheated as they couldn't convert. It reminds me of here. I remember that for 2 years, on the TV weather report each night after the news, the reporter would predict the temp for the next day-in both C & F.
Two years.
After that, it was reported in C only. I was fairly young at the time but I recall the rude awakening I felt because while it was reported in both, I had only really taken notice of the F. But we learnt to deal with it and built up our knowledge over time.
I doubt the young ones today can do it in reverse.
Americans find it extremely hard, even when simple ball park conversion are explained to them. That's because they don't use them often enough to remember them. They don't have to.
They don't want to convert, it wouldn't be a popular move, we won't see it happen until they absolutely have to.
I'd say a lot of them would be proud to be different.
They are very patriotic you know, much more so than your average Australian.
I always use the imperial system when designing and constructing my art quilts, but when it comes to purchasing the fabrics, it has to be by metric measurement in Australia of course, but imperial for USA fabric.
It's become second nature to me to use both systems automatically all the time even when cooking .. I don't know why, but I would find it hard to only think in just one system, it has to be both thought equally .. 
"I have a nephew named Miles, would be silly to call him 1.60934 kilometers"
