NASA also agreed with the logic of "sure, we don't know how it'll perform at low temperature, but we don't know that it won't work!" that led to the Challenger explosion. They aren't infallible and they can make extremely stupid mistakes too.
I'm an engineer, and the unit mixup you've linked isn't a failure of different unit systems, it's just shitty engineering. You should always label your units. There's several domains where even a single unit system has ambiguity without labeling -- pressure with bars, atmospheres, and kilopascals.
It was the contractor (I believe it was Lockheed?) who used pounds though NASA's documentation used metric units, cause they make actual scientific contributions.
You will constantly be switching back and forth and many of times using both at the same time. As an engineer who designs things built around the world, the most frustrating thing isn't when it is built in the US and it is (almost) all Imperial. It also isn't when it is built in Europe and everything is all Metric.
No, by far the most frustrating thing is when it is built in Mexico and our local teams have better access to Imperial raw material, but the local workers measure everything in metric. Such a damn mess - you have steel that is 1/2" thick, for example, but since it is Mexico we dimension it out to 12.7 mm, so nothing is ever a nice round number. And most threads are metric, but you can't get all components in metric, so on the same piece of equipment you could have an M10x1.25 bolt and a 3/8-16 bolt.
I'm British and it's sooo fun using older things that use strange measurements don't even make much sense even cook books use a mix of metric and imperial even to this day