You make projects to the buyers specs. But I have made US Customary machines and parts as requested by companies in India, Pakistan, and Great Britain if I remember correctly, (I've been out of the business for a good while and I'm now retired altogether). I can't remember anything in Germany or Japan. The Chinese were always whatever dope dreams they were on that particular day. They could be particularly bad about mixing and matching units for no reason or just making something up out of thin air.

Let's see, just off the top of head, US thread patterns are a bit better the the metric ones. While it doesn't mean as much these days thanks to CNC and G20/G21, (because the machines don't care). The inch pattern of threads are a little bit stronger, (it's not a whole lot more), and due to the threads per inch standard, it's easier to just count the number of threads over a set distance, (1 inch), vs trying to measure a thread crest to crest. This makes identifying threads pitches easier with inch pattern threads when trying to make repair parts. And back when manual machines ruled the shops, inch pattern threads made screw cutting lathes smaller, simpler, and cheaper than metric lathes. You needed fewer gears and shafts, fewer bearings, and less cast iron to make the head stock. This made US lathes faster and cheaper to make and cheaper to buy. Plus you can cut more different thread pitches on an inch pattern lathe vs a metric lathe due to not needing to resort to removing covers of the metric lathe to make gear changes and even swapping to a different threading dial despite the QC gear boxes.

These small cheap lathes is why, in their own small way, during WW2 the US industrial capabilities grew so fast. Anyone could buy a small lathe for a few hundred dollars, literally carry it up to as second story flat and start making all those small parts for the war effort. Small benchtop lathes were manufactured by the tens of thousands and they were all bought by people, many of whom had little to no experience in manufacturing to start making extra money in their off time from their day jobs. And while many got worn out and scrapped over the years, you can still find those little South Bend, Clausing, and Atlas lathes in hobby workshops in the US today. And they are lovingly used and doted over by their owners.

US Customary Units are slowly and surely fading into the sunset. And at some point they will just organically fade away, (it's why there has never been a national law forcing people to switch), as the casual US population just starts using them more and more. We already use the metric system to buy soda and whisk(e)y to searching for that missing 10mm wrench just like every one else on the planet. The only places you still see US Customary units being commonly used is in construction, (inches and feet), travel distances, (miles), and temperature, (Fahrenheit). Construction has backwards compatibility issues making it very difficult to switch from using a 2"x4" to a 50mmx100mm piece of lumber. Not to mention plumbing problems. And distances and speed limits on a road sign don't really make a lot of difference in how they are shown for the average traveler. And for deciding just how to dress for the weather, what units you are using really doesn't matter. (Why doesn't the metric world use Kelvin to measure the temperature in daily use?) It's not the first time a measurement system has been eclipsed in human history and even the metric system likely will get replaced by something else in the far future. In the end, neither system is head and shoulders better than the other. Nor have I ever claimed such. They both are, after all, just arbitrary units made up by some random dude hundreds of years ago.

G20/G21...........