I'd like to see more of this kind measurement expression in our modern vernaculars.
For example, an acre could be defined as 43560 sq ft, or 4047 meters, or .405 hectares, but these are arbitrary and don't tell me much. A more useful definition of acre is "the amount of land that a pair of oxen can plow in a day". Then, as a farmer, I don't really care how many square feet or square cubits or square whatever it is. I have a domain-specific (farming) definition that actually communicates something more useful to me than arbitrary distance units.
How is such a definition more useful? It's certainly not more useful to me. If someone tried to sell me such a quantity of land, the first thing I'd ask would be what the actual size is in standard units. A universal, precisely defined system of units is superior because it works in any context, you just need to know the system.
Expressing distance by travel time is a similarly stupid concept. I can tell someone something is 15 minutes by car, but here I'm expressing time, not distance. If I tell someone something is 15 meters away I'm expressing distance. The separate concepts of time and distance allow me to precisely express whatever I need to.
It's a tool that can be very helpful for describing the logistics of travel.
Depending on where you are and the context of the conversation, knowing that something is fifteen miles away might tell you shockingly little about the experience of getting there. There are places where that distance in one direction might take hours, but in another direction minutes. As you might imagine, this can be important to know.
I'd like to see more of this kind measurement expression in our modern vernaculars.
For example, an acre could be defined as 43560 sq ft, or 4047 meters, or .405 hectares, but these are arbitrary and don't tell me much. A more useful definition of acre is "the amount of land that a pair of oxen can plow in a day". Then, as a farmer, I don't really care how many square feet or square cubits or square whatever it is. I have a domain-specific (farming) definition that actually communicates something more useful to me than arbitrary distance units.