I remember a similar story from my father, of people in the small town he was in crowding standing in the front yard of a neighbor, crowding around a picture window to look in at the first TV in town in the mid-1950's.
I find it interesting, but I question how practical it is for regular use.
On a recent trip, I was driving in Canada in a car bought in the United States that did not have the metric values on the speedometer. But all of the posted speed limits were in values of 5 kph. Once you get that (roughly) 100 kph = 62 mph and 10 kph = 6 mph, there are some simple quick divisions or subtractions to convert the speed limit to close enough.