

I don’t think we’re going to solve a rational universal system of measurements on Beehaw. But the metre is most certainly not based on water; it’s the other way around.
We have so many systems at this point that traveling to space is an issue, which suggests the status quo isn’t working. What would you take as a base measurement instead of c?
You’re dancing around my point that for human-scale units, basing something off a constant makes sense. Sure, at AUs and light-years, numbers get messy, but that has nothing to do with buying flour. And using a measurement system based on measurements that will never change seems wise.