I know ISO 8601, but that doesn't answer my question. Let me rephrase this, why was a format intuitive to a machine chosen instead of a format which feels more intuitive to a human?
I think YYYY/MM/DD - YYYY/MM/DD will mean the correct thing to many more people than YYYY-MM-DD / YYYY-MM-DD, which I suspect many will interpret as an OR and not a RANGE.