There was once a time where standard was a thing. Living in a country using metric, if a recipe said a coffee cup I could use any coffee I, or my neighbour had, and have the exact mesurement. Then came cheap non-standard cup from China, then US-standard size of stuff no absolutely no reason. Now, I have to mesure my pillow before buying pillowcases because I can’t be use either the pillow or the case are following any standard from around the world.
The biggest problem with a standard is competing standards.
That being said, having different shapes makes it harder to measure things by eye. Even if all of your cups are the same volume, if they are different shapes that makes it harder to measure things consistently by eye. So I might make the same amount of coffee every day, using my carafe to measure the water and a scoop to measure the grounds, but unless I whip out measuring spoons for the milk I’m relying on a consistent container for that piece.
There was once a time where standard was a thing. Living in a country using metric, if a recipe said a coffee cup I could use any coffee I, or my neighbour had, and have the exact mesurement. Then came cheap non-standard cup from China, then US-standard size of stuff no absolutely no reason. Now, I have to mesure my pillow before buying pillowcases because I can’t be use either the pillow or the case are following any standard from around the world.
The biggest problem with a standard is competing standards.
That being said, having different shapes makes it harder to measure things by eye. Even if all of your cups are the same volume, if they are different shapes that makes it harder to measure things consistently by eye. So I might make the same amount of coffee every day, using my carafe to measure the water and a scoop to measure the grounds, but unless I whip out measuring spoons for the milk I’m relying on a consistent container for that piece.