DKP

I don’t think it’s a valid argument against metric, just a thought experiment to consider about the time needed to implement. Converting would be a slow process, but I agree it could be an economic boost as swapping things is a largely a manual process

Sometimes I like to think about the logistical challenges with a switch to metric. The one that always gives me pause is highway signs. Thinking about the monumental task of replacing every speed sign, distance sign, and mile marker across the country in any timely period makes my head hurt.

It could certainly be done, and is probably easier than I think with all the state DoTs working independently on it especially over time. We have a lot of road with a lot of signs.

You act like the two options are mutually exclusive.

There are 3 types of cones in the human eye, which reactive to different bands of the spectrum. They peak at approximately red, blue, and green. Our brains are good at combining that information to make it appear seamless. Colorblindness is generally a genetic defect in the production of one or more of those type of cones. https://askabiologist.asu.edu/rods-and-cones