Are they actually designed and manufactured in inches, or only marketed in inches?
Almost everyone called 90 mm floppy disks "3.5 inch", despite the fact the formal standard which defined their dimensions was metric. I believe the same was true of the "5.25 inch" disks which preceded them. (I think the original 8-inch floppy disks were non-metric though???)
Strictly speaking, this is also a consumer-oriented thing, using the diagonal. The diagonal is also misleading, because it gives no information about the dimensions and aspect ratio of a given panel. Consider a 15.6" 16:9 display, versus a (now increasingly more common) 16" 16:10 display.
Panel manufacturers are all based in Asia, and measure only the edges in millimetres, as they should. Even xrandr outputs EDID data in millimetres.
CRTs were 4:3 and tiny, they could fit basically everywhere. The diagonal was more than enough for consumers. Computer monitors started to have different ratios but they were not as widespread as today, even in a world of laptops and mobile devices.
The last time I had to buy a TV set I was more interested in the width of the appliance (screen plus bezel) than in its diagonal because I had to fit it into a set space. I went to a shop with a tape ruler.
Gas and water pipes are often in inches too (Italy) probably because it's an old and critical infrastructure and nobody wants to risk mistakes by trying to fit a 1 inch pipe with a 25 mm one, or 1 1/4" with a 32 mm. Close but not close enough.
However I guess that even American engines are measured in liters or cc, cubic centimeters.
> Gas and water pipes are often in inches too (Italy)
English inches (now 25.4 mm) or Italian inches? (“once”/“oncia”-varied in definition between different parts of Italy, but was always at least a fraction more or less than the English one)
I'm not sure I ever heard the Italian word oncia as a unit of length. I thought it was a translation of the imperial unit of weight, ounce. However all is possible in the world of the old semi forgotten traditional units.
